Amortization Schedule Calculator Balloon Payment

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Amortization Schedule Calculator with Balloon Payment

Calculate your loan amortization with a final balloon payment. Understand your payment structure, total interest, and the final lump sum.

The total amount borrowed.
Enter the yearly interest rate (e.g., 5 for 5%).
The total duration of the loan in years.
Monthly (12) Quarterly (4) Semi-Annually (2) Annually (1) How often payments are made each year.
The percentage of the original loan amount due at the end. Enter 0 for no balloon payment.
The year in which the balloon payment is due.

Loan Summary

0 Total Interest Paid
0 Total Payments
0 Balloon Payment

The monthly payment (M) is calculated using the formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1] where P is the principal loan amount, i is the monthly interest rate, and n is the total number of payments. The balloon payment is a percentage of the original loan amount due at a specified year. Total Interest Paid = (Total Payments) – (Loan Amount – Balloon Payment).

Amortization Over Time

This chart visualizes the remaining loan balance and the principal vs. interest paid over the life of the loan.

Balloon Payment Impact

This chart illustrates the loan balance reduction and the final balloon payment amount.

Understanding Amortization Schedules with Balloon Payments

What is an Amortization Schedule Calculator with Balloon Payment?

An amortization schedule calculator with a balloon payment is a specialized financial tool designed to help individuals and businesses understand the repayment structure of a loan that includes a large, lump-sum payment due at the end of its term. Unlike standard amortizing loans where the final payment fully repays the debt, a balloon loan has a series of smaller, regular payments that do not fully pay down the principal. Instead, a significant portion of the remaining principal, known as the balloon payment, is due on a specific date, typically at the end of the loan term or a predetermined year.

This type of calculator is crucial for anyone considering or currently managing a loan with a balloon clause. It provides clarity on how each payment is allocated between interest and principal, the total interest paid over time, the size of the regular payments, and, most importantly, the exact amount of the final balloon payment. Understanding these components is vital for financial planning, ensuring you can meet the final obligation.

Common misconceptions include believing that balloon loans are always cheaper or that the regular payments are significantly lower than a fully amortizing loan of the same term. While regular payments might be lower, the substantial final balloon payment requires careful saving and planning. Another misconception is that the balloon payment is simply the remaining balance; it's often a pre-agreed percentage of the original loan amount, which might be more or less than the actual remaining balance at that point.

Amortization Schedule with Balloon Payment Formula and Mathematical Explanation

Calculating an amortization schedule with a balloon payment involves several steps, combining standard amortization formulas with specific adjustments for the balloon feature. The core of the calculation relies on determining the regular payment amount, then tracking the principal and interest paid over time, and finally accounting for the balloon payment.

1. Calculating the Regular Payment (Assuming No Balloon Initially)

The standard formula for calculating the periodic payment (M) for an amortizing loan is:

M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1]

Where:

  • P = Principal Loan Amount
  • i = Periodic Interest Rate (Annual Rate / Number of Payments Per Year)
  • n = Total Number of Payments (Loan Term in Years * Number of Payments Per Year)

2. Adjusting for the Balloon Payment

A balloon loan is structured such that the regular payments are calculated as if the loan were amortizing over a *longer* term than the actual loan term, or the payments are calculated based on a specific amortization period, but the final balance is not zero. A common approach is to calculate payments based on a standard amortization schedule, but then a balloon payment is due at a specific point.

For a loan with a balloon payment due at a specific year (Balloon Year), the calculation becomes more complex. Often, the regular payment is calculated based on the original loan terms (P, i, n) as if it were a fully amortizing loan over the full term. However, at the specified Balloon Year, the remaining principal balance is due as the balloon payment. If the balloon payment is a fixed percentage of the original loan amount, it might differ from the actual remaining balance.

Let's consider the scenario where the balloon payment is a fixed percentage of the original loan amount, due at a specific year.

Balloon Payment Amount (B) = Original Loan Amount (P) * Balloon Payment Percentage

The regular payment (M) is calculated using the standard formula above. However, the total interest paid calculation needs adjustment. The loan is paid down over the term, but the final payment is the balloon amount. The total amount repaid will be the sum of all regular payments plus the balloon payment.

Total Payments Made = (Regular Payment M * Total Number of Payments n) + Balloon Payment B

Total Interest Paid = Total Payments Made – Original Loan Amount (P)

Note:** If the balloon payment is *less* than the remaining balance at the balloon year, the regular payments might be calculated based on a longer amortization period to ensure the balance is reduced sufficiently. If the balloon payment is a *fixed percentage* of the original loan, the calculation focuses on determining the regular payment that amortizes the loan down to the point where the remaining balance *equals* the specified balloon payment amount at the balloon year.

A more precise method for a fixed percentage balloon payment involves calculating the payment (M) such that the remaining balance at the balloon payment year equals the specified balloon amount.

Let P = Loan Amount, r = Annual Interest Rate, t = Loan Term in Years, f = Payments per Year, b = Balloon Payment Percentage, BY = Balloon Payment Year.

Monthly Interest Rate (i) = r / 100 / f

Total Number of Payments (n) = t * f

Balloon Payment Amount (B) = P * (b / 100)

Number of Payments until Balloon (n_b) = BY * f

The regular payment (M) is calculated to amortize the loan such that the remaining balance after n_b payments is B.

Remaining Balance Formula: Bal = P(1+i)^k – M[((1+i)^k – 1)/i]

Where k is the number of payments made. We need Bal = B when k = n_b.

B = P(1+i)^n_b – M[((1+i)^n_b – 1)/i]

Rearranging to solve for M:

M = [ P(1+i)^n_b – B ] * i / [ (1+i)^n_b – 1 ]

If B is 0 (no balloon), this simplifies to the standard amortization payment formula.

Variables Table

Variable Meaning Unit Typical Range
P (Loan Amount) The total amount of money borrowed. Currency ($) $10,000 – $1,000,000+
r (Annual Interest Rate) The yearly interest rate charged on the loan. Percentage (%) 1% – 20%+
t (Loan Term) The total duration of the loan. Years 1 – 30 years (common for mortgages), longer for commercial loans.
f (Payments Per Year) Frequency of payments (e.g., 12 for monthly). Count 1, 2, 4, 12
i (Periodic Interest Rate) The interest rate applied per payment period. Decimal (e.g., 0.05/12) Calculated (r / 100 / f)
n (Total Payments) The total number of payments over the loan's life. Count Calculated (t * f)
b (Balloon Payment Percentage) The percentage of the original loan amount due as a final lump sum. Percentage (%) 0% – 100%
BY (Balloon Payment Year) The year in which the balloon payment is due. Year 1 – t
B (Balloon Payment Amount) The actual monetary value of the balloon payment. Currency ($) Calculated (P * b / 100)
M (Regular Payment) The fixed amount paid periodically throughout the loan term (excluding the balloon). Currency ($) Calculated
Total Interest Paid The sum of all interest paid over the life of the loan. Currency ($) Calculated

Practical Examples (Real-World Use Cases)

Example 1: Commercial Real Estate Loan

A business owner takes out a $500,000 commercial loan to purchase a new office building. The loan has an annual interest rate of 6.5%, a term of 20 years, and payments are made monthly. The loan agreement includes a balloon payment of 30% of the original loan amount due at the end of year 10.

Inputs:

  • Loan Amount (P): $500,000
  • Annual Interest Rate (r): 6.5%
  • Loan Term (t): 20 years
  • Payments Per Year (f): 12
  • Balloon Payment Percentage (b): 30%
  • Balloon Payment Year (BY): 10

Calculations:

  • Monthly Interest Rate (i) = 6.5% / 12 = 0.00541667
  • Total Payments (n) = 20 * 12 = 240
  • Balloon Payment Amount (B) = $500,000 * 0.30 = $150,000
  • Payments until Balloon (n_b) = 10 * 12 = 120
  • Regular Payment (M) = [ $500,000 * (1 + 0.00541667)^120 – $150,000 ] * 0.00541667 / [ (1 + 0.00541667)^120 – 1 ] ≈ $3,177.79
  • Total Paid in Regular Payments = $3,177.79 * 120 = $381,334.80
  • Total Payments Made = $381,334.80 + $150,000 = $531,334.80
  • Total Interest Paid = $531,334.80 – $500,000 = $31,334.80

Interpretation: The business owner will make regular monthly payments of approximately $3,177.79 for 10 years. At the end of year 10, they will owe a balloon payment of $150,000. The total interest paid over the 10 years leading up to the balloon payment is $31,334.80. This structure allows for lower initial cash outflows compared to a fully amortizing loan over 20 years, but requires significant planning to meet the $150,000 balloon payment.

Example 2: Equipment Financing with a Shorter Balloon Term

A small business purchases specialized machinery for $80,000. The financing agreement is for 5 years with an annual interest rate of 8%, paid quarterly. A balloon payment of 15% of the original amount is due at the end of year 3.

Inputs:

  • Loan Amount (P): $80,000
  • Annual Interest Rate (r): 8%
  • Loan Term (t): 5 years
  • Payments Per Year (f): 4
  • Balloon Payment Percentage (b): 15%
  • Balloon Payment Year (BY): 3

Calculations:

  • Quarterly Interest Rate (i) = 8% / 4 = 2% = 0.02
  • Total Payments (n) = 5 * 4 = 20
  • Balloon Payment Amount (B) = $80,000 * 0.15 = $12,000
  • Payments until Balloon (n_b) = 3 * 4 = 12
  • Regular Payment (M) = [ $80,000 * (1 + 0.02)^12 – $12,000 ] * 0.02 / [ (1 + 0.02)^12 – 1 ] ≈ $7,448.94
  • Total Paid in Regular Payments = $7,448.94 * 12 = $89,387.28
  • Total Payments Made = $89,387.28 + $12,000 = $101,387.28
  • Total Interest Paid = $101,387.28 – $80,000 = $21,387.28

Interpretation: The business will make quarterly payments of approximately $7,448.94 for the first 3 years. At the end of year 3, a balloon payment of $12,000 is due. The total interest paid over these 3 years is $21,387.28. This structure helps manage cash flow in the initial years of using the machinery, but the business must be prepared for the $12,000 lump sum.

How to Use This Amortization Schedule Calculator with Balloon Payment

Using this calculator is straightforward and designed to provide immediate insights into your loan's financial structure. Follow these steps:

  1. Enter Loan Amount: Input the total principal amount you borrowed.
  2. Input Annual Interest Rate: Enter the yearly interest rate as a percentage (e.g., 5 for 5%).
  3. Specify Loan Term: Enter the total number of years the loan is scheduled to last.
  4. Select Payment Frequency: Choose how often payments are made per year (e.g., Monthly, Quarterly).
  5. Enter Balloon Payment Percentage: Input the percentage of the original loan amount that will be due as a final balloon payment. Enter 0 if there is no balloon payment.
  6. Specify Balloon Payment Year: Enter the year in which the balloon payment is due. This must be within the loan term.
  7. Click 'Calculate': Once all fields are populated, click the 'Calculate' button.

How to Read Results:

  • Primary Highlighted Result (Regular Payment): This is the fixed amount you'll pay periodically throughout the loan term, excluding the balloon payment.
  • Total Interest Paid: The cumulative interest you will pay over the entire loan period, including the interest accrued up to the balloon payment.
  • Total Payments: The sum of all regular payments plus the final balloon payment.
  • Balloon Payment: The specific lump sum amount due at the end of the specified balloon year.
  • Amortization Table: This table breaks down each payment, showing the payment number, date, payment amount, interest paid, principal paid, and the remaining balance. This provides a detailed view of how your loan is paid down over time.
  • Charts: The charts offer a visual representation of the loan balance reduction and the breakdown of principal versus interest paid.

Decision-Making Guidance:

This calculator helps you assess affordability and plan for the future. If the calculated regular payment is manageable, but the balloon payment seems daunting, consider:

  • Saving Strategy: Start saving early for the balloon payment. The calculator's results can help you determine how much you need to set aside each period.
  • Refinancing Options: Explore refinancing options before the balloon payment is due. You might be able to refinance the remaining balance into a new loan, potentially with different terms.
  • Loan Modification: In some cases, lenders may allow you to modify the loan to amortize the remaining balance over a longer period, effectively converting it into a traditional loan.
  • Comparing Loan Options: Use the calculator to compare different loan scenarios (e.g., varying balloon percentages or terms) to find the most suitable option for your financial situation.

Key Factors That Affect Amortization Schedule with Balloon Payment Results

Several critical factors influence the outcome of your amortization schedule and the final balloon payment. Understanding these can help you negotiate better loan terms and plan more effectively:

  1. Loan Amount (Principal): A larger principal loan amount naturally leads to higher regular payments and a larger potential balloon payment, assuming other factors remain constant. This is the foundational element of any loan calculation.
  2. Annual Interest Rate: This is one of the most significant factors. A higher interest rate increases both the periodic interest paid and the total interest over the loan's life. It also increases the regular payment amount required to amortize the loan, especially if the balloon payment is substantial. Even small differences in rates compound significantly over time.
  3. Loan Term: A longer loan term generally results in lower regular payments because the principal is spread over more periods. However, it also means paying more interest overall. For balloon loans, the term influences the total number of payments before the balloon is due and the remaining balance at that point.
  4. Payment Frequency: More frequent payments (e.g., monthly vs. annually) lead to slightly lower total interest paid over the life of a standard loan because principal is paid down faster. For balloon loans, it affects the number of payments until the balloon is due and the calculation of the periodic interest rate.
  5. Balloon Payment Percentage and Year: The size of the balloon payment (percentage of the original loan) and when it's due directly impacts the required regular payment. A larger balloon payment or an earlier due date necessitates higher regular payments to ensure the remaining balance matches the balloon amount by the due date. A smaller or later balloon payment allows for lower regular payments.
  6. Loan Fees and Closing Costs: While not directly part of the amortization calculation itself, upfront fees (origination fees, appraisal fees, legal costs) increase the total cost of borrowing. These should be factored into your overall financial decision when considering a loan.
  7. Economic Conditions (Inflation & Interest Rate Environment): Future economic conditions can affect your ability to manage the balloon payment. If interest rates rise significantly before the balloon payment is due, refinancing might become more expensive. Conversely, falling rates could make refinancing attractive. Inflation impacts the purchasing power of money, affecting how burdensome the balloon payment feels in the future.
  8. Prepayment Penalties: Some loans may include penalties for paying off the loan early or making extra principal payments. This can affect your flexibility if you plan to pay down the principal faster to reduce the balloon amount or avoid it altogether.

Frequently Asked Questions (FAQ)

Q1: What is the main advantage of a balloon loan?

The primary advantage is typically lower regular payments compared to a fully amortizing loan over the same initial term. This can improve cash flow, especially for businesses or individuals needing immediate capital without the burden of higher immediate payments.

Q2: What are the biggest risks of a balloon loan?

The main risk is the substantial balloon payment due at the end. If you haven't saved adequately or cannot refinance the loan, you could face default. Interest rate risk is also a factor; if rates rise, refinancing the balloon payment might be more expensive than anticipated.

Q3: Can I avoid the balloon payment?

Ideally, you should plan to either pay the balloon payment in full when it's due or refinance the remaining balance into a new loan. Some lenders may offer loan modifications to convert the balloon loan into a fully amortizing loan, but this is not guaranteed and may involve new terms.

Q4: How is the balloon payment calculated if it's a percentage of the original loan?

It's calculated by multiplying the original loan amount by the specified balloon payment percentage. For example, a $100,000 loan with a 20% balloon payment means the balloon payment will be $20,000.

Q5: What happens if I can't afford the balloon payment?

If you cannot pay the balloon payment or refinance, you risk defaulting on the loan. This can lead to foreclosure (for real estate) or repossession (for equipment), damage your credit score, and result in legal action.

Q6: Is a balloon loan suitable for a primary residence mortgage?

Balloon loans are generally not recommended for primary residences due to the significant risk associated with the large final payment. Standard 15-year or 30-year fixed-rate mortgages are far more common and safer for homeowners.

Q7: How does the balloon payment year affect my regular payments?

The earlier the balloon payment is due (i.e., a smaller Balloon Payment Year), the higher your regular payments will need to be. This is because the principal needs to be reduced more significantly in fewer periods to reach the target balloon amount by the due date.

Q8: Can I make extra payments to reduce the balloon amount?

Yes, you can often make extra principal payments. This will reduce the outstanding balance faster, potentially lowering the final balloon payment amount or even eliminating it if you pay down enough principal. However, check your loan agreement for any prepayment penalties.

Q9: What is the difference between a balloon loan and an interest-only loan?

An interest-only loan requires payments that only cover the interest for a set period; the principal remains unchanged. At the end of the interest-only period, the full principal is typically due, or the loan converts to a fully amortizing payment. A balloon loan has regular payments that include some principal reduction, but a significant portion of the principal remains for a large final balloon payment.

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var loanAmount = parseFloat(loanAmountInput.value); var annualInterestRate = parseFloat(annualInterestRateInput.value); var loanTermYears = parseInt(loanTermYearsInput.value); var paymentFrequency = parseInt(paymentFrequencyInput.value); var balloonPaymentPercentage = parseFloat(balloonPaymentPercentageInput.value); var balloonPaymentYear = parseInt(balloonPaymentYearInput.value); if (isNaN(loanAmount) || loanAmount <= 0) { showError(loanAmountError, 'Please enter a valid loan amount.'); isValid = false; } else { hideError(loanAmountError); } if (isNaN(annualInterestRate) || annualInterestRate 100) { showError(annualInterestRateError, 'Please enter a rate between 0% and 100%.'); isValid = false; } else { hideError(annualInterestRateError); } if (isNaN(loanTermYears) || loanTermYears <= 0) { showError(loanTermYearsError, 'Please enter a valid loan term in years.'); isValid = false; } else { hideError(loanTermYearsError); } if (isNaN(paymentFrequency) || paymentFrequency <= 0) { showError(paymentFrequencyError, 'Please select a valid payment frequency.'); isValid = false; } else { hideError(paymentFrequencyError); } if (isNaN(balloonPaymentPercentage) || balloonPaymentPercentage 100) { showError(balloonPaymentPercentageError, 'Please enter a percentage between 0% and 100%.'); isValid = false; } else { hideError(balloonPaymentPercentageError); } if (isNaN(balloonPaymentYear) || balloonPaymentYear loanTermYears) { showError(balloonPaymentYearError, 'Balloon year must be between 1 and the loan term.'); isValid = false; } else { hideError(balloonPaymentYearError); } return isValid; } function calculateAmortization() { if (!validateInputs()) { resultsContainer.style.display = 'none'; chartContainer.style.display = 'none'; balloonChartContainer.style.display = 'none'; return; } var principal = parseFloat(loanAmountInput.value); var annualRate = parseFloat(annualInterestRateInput.value); var termYears = parseInt(loanTermYearsInput.value); var freq = parseInt(paymentFrequencyInput.value); var balloonPercent = parseFloat(balloonPaymentPercentageInput.value); var balloonYear = parseInt(balloonPaymentYearInput.value); var monthlyRate = annualRate / 100 / freq; var numberOfPayments = termYears * freq; var balloonAmount = principal * (balloonPercent / 100); var paymentsToBalloon = balloonYear * freq; var regularPayment = 0; var totalInterestPaid = 0; var totalPaymentsMade = 0; var remainingBalance = principal; var amortizationData = []; var principalPaidData = []; var interestPaidData = []; var remainingBalanceData = []; var paymentDates = []; // Calculate regular payment using the formula adjusted for balloon payment if (balloonPercent === 0) { // Standard amortization if no balloon payment if (monthlyRate > 0) { regularPayment = principal * (monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) / (Math.pow(1 + monthlyRate, numberOfPayments) – 1); } else { regularPayment = principal / numberOfPayments; } } else { // Formula for payment with a balloon // M = [ P(1+i)^n_b – B ] * i / [ (1+i)^n_b – 1 ] if (Math.pow(1 + monthlyRate, paymentsToBalloon) – 1 === 0) { // Avoid division by zero if rate is 0 regularPayment = (principal – balloonAmount) / paymentsToBalloon; } else { regularPayment = (principal * Math.pow(1 + monthlyRate, paymentsToBalloon) – balloonAmount) * monthlyRate / (Math.pow(1 + monthlyRate, paymentsToBalloon) – 1); } if (isNaN(regularPayment) || regularPayment < 0) { // Fallback if calculation yields invalid result regularPayment = principal / numberOfPayments; // Use a simpler estimate } } var currentBalance = principal; var cumulativeInterest = 0; var cumulativePrincipal = 0; var totalPaid = 0; for (var i = 0; i 0) { principalPayment = currentBalance – balloonAmount; interestPayment = regularPayment – principalPayment; // Recalculate interest for this specific payment if (principalPayment < 0) principalPayment = currentBalance; // Ensure principal doesn't go negative if (interestPayment < 0) interestPayment = 0; // Ensure interest doesn't go negative regularPayment = principalPayment + interestPayment; // Adjust regular payment for this specific period } else if (i === numberOfPayments – 1 && balloonPercent === 0) { // Standard last payment adjustment principalPayment = currentBalance; interestPayment = regularPayment – principalPayment; if (interestPayment = paymentsToBalloon && balloonPercent > 0) { // After balloon payment, remaining payments should clear the balance // This scenario implies the balloon payment was less than remaining balance // and the loan continues. For simplicity, we assume the balloon payment // is the final payment or the loan is structured such that the regular // payment clears the remaining balance after the balloon. // If the balloon payment is a fixed percentage, and it's less than the remaining balance, // the loan might continue or be refinanced. // For this calculator, we assume the balloon payment is the final obligation. // If the balloon payment is due, and there are more payments, we need to recalculate. // A common structure is that the balloon payment IS the final payment. // If the balloon payment is due at year X, and the loan term is Y > X, // the loan might be structured to amortize the remaining balance after the balloon. // For this calculator, we'll assume the balloon payment is the final obligation. // If the balloon payment is due, and it's not the last payment, // we need to adjust the calculation. // Let's assume the balloon payment is the final payment due. // If balloonYear < termYears, the loan might be structured differently. // For this calculator, we'll assume the balloon payment is the final obligation. // If balloonYear = paymentsToBalloon, the loan is considered paid off by the balloon. // We will stop adding payments after the balloon payment is conceptually made. // However, the loop continues to generate data points. // Let's adjust the logic: if balloon is paid, remaining balance is 0. principalPayment = 0; interestPayment = 0; regularPayment = 0; } if (currentBalance 0) { // Find the balance at the balloon payment year var balanceAtBalloonYear = principal; for (var j = 0; j < paymentsToBalloon; j++) { var interest = balanceAtBalloonYear * monthlyRate; var principalPaid = regularPayment – interest; if (principalPaid < 0) principalPaid = 0; // Should not happen with correct regularPayment calculation balanceAtBalloonYear -= principalPaid; if (balanceAtBalloonYear < 0.01) balanceAtBalloonYear = 0; } finalBalloonActual = balanceAtBalloonYear; // This is the actual remaining balance // The balloon payment is either the calculated percentage or the remaining balance, whichever is specified/relevant. // Our calculator uses the percentage. If the percentage results in a balloon payment // that is LESS than the remaining balance, the borrower still owes the remaining balance. // If the percentage results in a balloon payment MORE than the remaining balance, // the borrower only owes the remaining balance. // For simplicity, we'll use the calculated balloonAmount (percentage) and assume it's the target. // The total interest calculation needs to be precise. var totalRegularPaymentsSum = 0; for(var k=0; k < amortizationData.length; k++) { if (k item.balance); var principalPaidCumulative = []; var interestPaidCumulative = []; var currentPrincipalSum = 0; var currentInterestSum = 0; for(var i=0; i 10 ? 10 : amortizationData.length); g.append("g") .attr("transform", "translate(0," + innerHeight + ")") .call(xAxis) .selectAll("text") .style("text-anchor", "end") .attr("dx", "-.8em") .attr("dy", ".15em") .attr("transform", "rotate(-45)"); // Y-axis var yAxis = d3.axisLeft(yScale); g.append("g").call(yAxis); // Labels g.append("text") .attr("class", "x label") .attr("text-anchor", "middle") .attr("x", innerWidth / 2) .attr("y", innerHeight + margin.bottom – 10) .text("Payment Number"); g.append("text") .attr("class", "y label") .attr("text-anchor", "middle") .attr("y", -margin.left + 20) .attr("x", -innerHeight / 2) .attr("dy", ".75em") .attr("transform", "rotate(-90)") .text("Loan Balance ($)"); // Data Series 1: Remaining Balance var balanceLine = d3.line() .x(function(d, i) { return xScale(i); }) .y(function(d) { return yScale(d.balance); }) .curve(d3.curveMonotoneX); g.append("path") .datum(amortizationData.slice(0, paymentsToBalloon)) // Data up to balloon payment .attr("fill", "none") .attr("stroke", "steelblue") .attr("stroke-width", 2) .attr("d", balanceLine); // Data Series 2: Balloon Payment Target (represented as a horizontal line) // We need to show the target balloon amount at the balloon payment year. // Let's represent the target balloon amount as a point or a line segment. // A simpler approach: show the remaining balance *after* the balloon payment. // Or, show the principal paid up to the balloon payment. // Let's show the remaining balance line and the target balloon amount line. var targetBalloonY = yScale(balloonAmount); g.append("line") .attr("x1", xScale(0)) .attr("x2", xScale(paymentsToBalloon)) .attr("y1", targetBalloonY) .attr("y2", targetBalloonY) .attr("stroke", "red") .attr("stroke-width", 2) .attr("stroke-dasharray", "5,5"); // Add a label for the balloon payment line g.append("text") .attr("x", xScale(paymentsToBalloon) + 5) .attr("y", targetBalloonY – 5) .attr("fill", "red") .style("font-size", "12px") .text("Balloon Target"); // Add a point for the balloon payment itself if (amortizationData.length >= paymentsToBalloon) { var balloonPaymentPoint = amortizationData[paymentsToBalloon – 1]; g.append("circle") .attr("cx", xScale(paymentsToBalloon)) .attr("cy", yScale(balloonPaymentPoint.balance)) // This is the actual balance *before* the balloon payment is applied .attr("r", 5) .attr("fill", "red"); // Add text label for the balloon payment amount g.append("text") .attr("x", xScale(paymentsToBalloon) + 10) .attr("y", yScale(balloonPaymentPoint.balance) – 10) .attr("fill", "red") .style("font-size", "12px") .text("Balloon Due: " + formatCurrency(balloonAmount)); } // Legend g.append("circle").attr("cx", 50).attr("cy", -10).attr("r", 4).style("fill", "steelblue"); g.append("text").attr("x", 60).attr("y", -10).text("Remaining Balance").style("font-size", "12px").attr("alignment-baseline", "middle"); g.append("line").attr("x1", 150).attr("x2", 190).attr("y1", -10).attr("y2", -10).attr("stroke", "red").style("stroke-dasharray", "3,3"); g.append("text").attr("x", 200).attr("y", -10).text("Balloon Target").style("font-size", "12px").attr("alignment-baseline", "middle"); } function resetForm() { loanAmountInput.value = '200000'; annualInterestRateInput.value = '5'; loanTermYearsInput.value = '30'; paymentFrequencyInput.value = '12'; balloonPaymentPercentageInput.value = '20'; balloonPaymentYearInput.value = '5'; hideError(loanAmountError); hideError(annualInterestRateError); hideError(loanTermYearsError); hideError(paymentFrequencyError); hideError(balloonPaymentPercentageError); hideError(balloonPaymentYearError); resultsContainer.style.display = 'none'; chartContainer.style.display = 'none'; balloonChartContainer.style.display = 'none'; } function copyResults() { var principal = parseFloat(loanAmountInput.value); var annualRate = parseFloat(annualInterestRateInput.value); var termYears = parseInt(loanTermYearsInput.value); var freq = parseInt(paymentFrequencyInput.value); var balloonPercent = parseFloat(balloonPaymentPercentageInput.value); var balloonYear = parseInt(balloonPaymentYearInput.value); var monthlyRate = annualRate / 100 / freq; var numberOfPayments = termYears * freq; var balloonAmount = principal * (balloonPercent / 100); var paymentsToBalloon = balloonYear * freq; var regularPayment = 0; var totalInterestPaid = 0; var totalPaymentsMade = 0; if (balloonPercent === 0) { if (monthlyRate > 0) { regularPayment = principal * (monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) / (Math.pow(1 + monthlyRate, numberOfPayments) – 1); } else { regularPayment = principal / numberOfPayments; } } else { if (Math.pow(1 + monthlyRate, paymentsToBalloon) – 1 === 0) { regularPayment = (principal – balloonAmount) / paymentsToBalloon; } else { regularPayment = (principal * Math.pow(1 + monthlyRate, paymentsToBalloon) – balloonAmount) * monthlyRate / (Math.pow(1 + monthlyRate, paymentsToBalloon) – 1); } if (isNaN(regularPayment) || regularPayment < 0) { regularPayment = principal / numberOfPayments; } } var currentBalance = principal; var cumulativeInterest = 0; var totalPaid = 0; for (var i = 0; i 0) { principalPayment = currentBalance – balloonAmount; interestPayment = regularPayment – principalPayment; if (principalPayment < 0) principalPayment = currentBalance; if (interestPayment < 0) interestPayment = 0; regularPayment = principalPayment + interestPayment; } else if (i === numberOfPayments – 1 && balloonPercent === 0) { principalPayment = currentBalance; interestPayment = regularPayment – principalPayment; if (interestPayment = paymentsToBalloon && balloonPercent > 0) { principalPayment = 0; interestPayment = 0; regularPayment = 0; } if (currentBalance 0) { var totalRegularPaymentsSum = 0; for(var k=0; k < paymentsToBalloon; k++) { totalRegularPaymentsSum += amortizationData[k].paymentAmount; // Need amortizationData populated } // Re-calculate total interest and payments based on the generated amortizationData var tempAmortizationData = []; var tempCurrentBalance = principal; var tempRegularPayment = regularPayment; // Use the calculated regular payment for (var i = 0; i 0) { principalPayment = tempCurrentBalance – balloonAmount; interestPayment = tempRegularPayment – principalPayment; if (principalPayment < 0) principalPayment = tempCurrentBalance; if (interestPayment < 0) interestPayment = 0; tempRegularPayment = principalPayment + interestPayment; } else if (i === numberOfPayments – 1 && balloonPercent === 0) { principalPayment = tempCurrentBalance; interestPayment = tempRegularPayment – principalPayment; if (interestPayment = paymentsToBalloon && balloonPercent > 0) { principalPayment = 0; interestPayment = 0; tempRegularPayment = 0; } if (tempCurrentBalance < 0.01) { tempCurrentBalance = 0; interestPayment = 0; principalPayment = 0; } tempCurrentBalance -= principalPayment; tempAmortizationData.push({ paymentAmount: tempRegularPayment, interest: interestPayment, principal: principalPayment }); } var sumOfRegularPayments = 0; for(var m=0; m < tempAmortizationData.length; m++) { if (m 0) { textToCopy += "Balloon Payment Percentage: " + formatPercentage(balloonPercent) + "\n"; textToCopy += "Balloon Payment Year: " + balloonYear + "\n"; } textToCopy += "\n— Key Results —\n"; textToCopy += "Regular Payment: " + formatCurrency(regularPayment) + "\n"; textToCopy += "Total Interest Paid: " + formatCurrency(totalInterestPaid) + "\n"; textToCopy += "Total Payments Made: " + formatCurrency(totalPaymentsMade) + "\n"; if (balloonPercent > 0) { textToCopy += "Final Balloon Payment: " + formatCurrency(balloonAmount) + "\n"; } // Use a temporary textarea to copy text var textArea = document.createElement("textarea"); textArea.value = textToCopy; textArea.style.position = "fixed"; textArea.style.left = "-9999px"; document.body.appendChild(textArea); textArea.focus(); textArea.select(); try { var successful = document.execCommand('copy'); var msg = successful ? 'Results copied!' : 'Copy failed!'; console.log(msg); // Optionally show a temporary message to the user var copyButton = document.querySelector('.btn-copy'); var originalText = copyButton.textContent; copyButton.textContent = msg; setTimeout(function() { copyButton.textContent = originalText; }, 2000); } catch (err) { console.log('Oops, unable to copy'); } document.body.removeChild(textArea); } // Initial calculation on page load if inputs have default values document.addEventListener('DOMContentLoaded', function() { // Check if inputs have default values and calculate if they do if (loanAmountInput.value && annualInterestRateInput.value && loanTermYearsInput.value && paymentFrequencyInput.value) { calculateAmortization(); } }); // Add event listeners for real-time updates loanAmountInput.addEventListener('input', calculateAmortization); annualInterestRateInput.addEventListener('input', calculateAmortization); loanTermYearsInput.addEventListener('input', calculateAmortization); paymentFrequencyInput.addEventListener('change', calculateAmortization); balloonPaymentPercentageInput.addEventListener('input', calculateAmortization); balloonPaymentYearInput.addEventListener('input', calculateAmortization); // Load D3.js for SVG chart if not already loaded if (typeof d3 === 'undefined') { var script = document.createElement('script'); script.src = 'https://d3js.org/d3.v7.min.js'; script.onload = function() { // D3 is loaded, now load Chart.js if (typeof Chart === 'undefined') { var chartScript = document.createElement('script'); chartScript.src = 'https://cdn.jsdelivr.net/npm/chart.js@3.7.0/dist/chart.min.js'; chartScript.onload = function() { // Both libraries loaded, perform initial calculation if needed if (loanAmountInput.value && annualInterestRateInput.value && loanTermYearsInput.value && paymentFrequencyInput.value) { calculateAmortization(); } }; document.head.appendChild(chartScript); } else { // Chart.js already loaded if (loanAmountInput.value && annualInterestRateInput.value && loanTermYearsInput.value && paymentFrequencyInput.value) { calculateAmortization(); } } }; document.head.appendChild(script); } else { // D3 is already loaded if (typeof Chart === 'undefined') { var chartScript = document.createElement('script'); chartScript.src = 'https://cdn.jsdelivr.net/npm/chart.js@3.7.0/dist/chart.min.js'; chartScript.onload = function() { if (loanAmountInput.value && annualInterestRateInput.value && loanTermYearsInput.value && paymentFrequencyInput.value) { calculateAmortization(); } }; document.head.appendChild(chartScript); } else { // Both libraries already loaded if (loanAmountInput.value && annualInterestRateInput.value && loanTermYearsInput.value && paymentFrequencyInput.value) { calculateAmortization(); } } }

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