Amortize a Loan Calculator

Amortize a Loan Calculator: Calculate Loan Payments & Schedule :root { –primary-color: #004a99; –success-color: #28a745; –background-color: #f8f9fa; –text-color: #333; –border-color: #ddd; –shadow-color: rgba(0, 0, 0, 0.1); –card-background: #ffffff; –error-color: #dc3545; } body { font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif; background-color: var(–background-color); color: var(–text-color); line-height: 1.6; margin: 0; padding: 0; } .container { max-width: 1000px; margin: 20px auto; padding: 20px; background-color: var(–card-background); border-radius: 8px; box-shadow: 0 2px 10px var(–shadow-color); } h1, h2, h3 { color: var(–primary-color); text-align: center; margin-bottom: 20px; } h1 { font-size: 2.5em; } h2 { font-size: 1.8em; margin-top: 30px; border-bottom: 2px solid var(–primary-color); padding-bottom: 10px; } h3 { font-size: 1.4em; margin-top: 25px; color: var(–primary-color); } .loan-calc-container { background-color: var(–card-background); padding: 25px; border-radius: 8px; box-shadow: 0 0 15px var(–shadow-color); margin-bottom: 30px; } .input-group { margin-bottom: 20px; position: relative; } .input-group label { display: block; margin-bottom: 8px; font-weight: bold; color: var(–primary-color); } .input-group input[type="number"], .input-group input[type="text"], .input-group select { width: calc(100% – 22px); /* Account for padding and border */ padding: 10px 10px; border: 1px solid var(–border-color); border-radius: 4px; font-size: 1em; box-sizing: border-box; /* Include padding and border in the element's total width and height */ } .input-group input[type="number"]:focus, .input-group input[type="text"]:focus, .input-group select:focus { border-color: var(–primary-color); outline: none; box-shadow: 0 0 5px rgba(0, 74, 153, 0.3); } .input-group .helper-text { font-size: 0.85em; color: #6c757d; margin-top: 5px; display: block; } .error-message { color: var(–error-color); font-size: 0.85em; margin-top: 5px; display: none; /* Hidden by default */ } .button-group { display: flex; justify-content: center; gap: 15px; margin-top: 30px; flex-wrap: wrap; } button { background-color: var(–primary-color); color: white; border: none; padding: 12px 25px; border-radius: 5px; cursor: pointer; font-size: 1.05em; transition: background-color 0.3s ease, transform 0.2s ease; font-weight: bold; } button:hover { background-color: #003366; transform: translateY(-2px); } button.reset-button { background-color: #6c757d; } button.reset-button:hover { background-color: #5a6268; } button.copy-button { background-color: var(–success-color); } button.copy-button:hover { background-color: #218838; } .results-container { margin-top: 30px; padding: 20px; background-color: var(–background-color); border: 1px solid var(–border-color); border-radius: 8px; text-align: center; } .results-container h3 { margin-top: 0; } .main-result { font-size: 2.5em; font-weight: bold; color: var(–primary-color); background-color: #e7f3ff; padding: 15px; border-radius: 8px; margin-bottom: 20px; display: inline-block; /* To allow background to wrap content */ } .intermediate-results { display: flex; justify-content: space-around; gap: 20px; margin-bottom: 20px; flex-wrap: wrap; } .intermediate-results .result-item { text-align: center; padding: 10px; background-color: var(–card-background); border: 1px solid var(–border-color); border-radius: 5px; flex: 1; min-width: 150px; } .intermediate-results .result-item h4 { font-size: 1.1em; color: var(–primary-color); margin-bottom: 5px; } .intermediate-results .result-item p { font-size: 1.5em; font-weight: bold; margin: 0; color: var(–text-color); } .formula-explanation { font-size: 0.9em; color: #6c757d; margin-top: 15px; padding: 10px; background-color: #f0f5fa; border-radius: 5px; } .amortization-table, .chart-container { margin-top: 30px; background-color: var(–card-background); padding: 20px; border-radius: 8px; box-shadow: 0 0 15px var(–shadow-color); } caption { font-size: 1.2em; font-weight: bold; color: var(–primary-color); margin-bottom: 15px; caption-side: top; text-align: center; } table { width: 100%; border-collapse: collapse; margin-top: 10px; } th, td { border: 1px solid var(–border-color); padding: 10px 12px; text-align: right; } th { background-color: #e7f3ff; color: var(–primary-color); font-weight: bold; text-align: center; } td { background-color: var(–card-background); } tbody tr:nth-child(even) td { background-color: #f0f5fa; } canvas { display: block; margin: 20px auto; max-width: 100%; } .chart-legend { text-align: center; margin-top: 10px; font-size: 0.9em; color: #555; } .chart-legend span { display: inline-block; margin: 0 10px; position: relative; padding-left: 15px; } .chart-legend span::before { content: "; display: inline-block; width: 10px; height: 10px; position: absolute; left: 0; top: 50%; transform: translateY(-50%); border-radius: 2px; } .legend-principal::before { background-color: #36a2eb; /* Example color for principal */ } .legend-interest::before { background-color: #ff6384; /* Example color for interest */ } .article-content { background-color: var(–card-background); padding: 30px; border-radius: 8px; box-shadow: 0 2px 10px var(–shadow-color); margin-top: 30px; } .article-content p, .article-content ul, .article-content ol { margin-bottom: 15px; color: var(–text-color); } .article-content a { color: var(–primary-color); text-decoration: none; } .article-content a:hover { text-decoration: underline; } .article-content ul, .article-content ol { padding-left: 25px; } .article-content li { margin-bottom: 8px; } .article-content strong, .article-content b { color: #003366; } .faq-section h3, .factor-section h3 { text-align: left; margin-top: 0; } .faq-item, .factor-item { margin-bottom: 20px; padding: 15px; background-color: #f0f5fa; border-left: 5px solid var(–primary-color); border-radius: 4px; } .faq-item strong, .factor-item strong { display: block; margin-bottom: 5px; color: var(–primary-color); font-size: 1.1em; } .related-tools ul { list-style: none; padding: 0; } .related-tools li { margin-bottom: 15px; padding: 10px; background-color: #e7f3ff; border-radius: 4px; } .related-tools li a { font-weight: bold; display: block; color: var(–primary-color); } .related-tools li p { margin-top: 5px; margin-bottom: 0; font-size: 0.9em; color: #555; } /* Responsive adjustments */ @media (max-width: 768px) { .container { margin: 10px; padding: 15px; } h1 { font-size: 2em; } h2 { font-size: 1.5em; } .intermediate-results { flex-direction: column; align-items: center; } .intermediate-results .result-item { width: 90%; margin-bottom: 15px; } button { width: 100%; margin-bottom: 10px; } .button-group { flex-direction: column; align-items: center; } .button-group button { width: 80%; } .amortization-table, .chart-container { overflow-x: auto; /* Allow horizontal scrolling for tables on small screens */ } }

Amortize a Loan Calculator

Calculate your loan payments, total interest, and generate an amortization schedule. Understand your loan repayment journey.

Loan Amortization Calculator

The total amount of money borrowed.
The yearly interest rate on the loan.
The total duration of the loan in years.
12 (Monthly) 4 (Quarterly) 2 (Semi-annually) 1 (Annually) How often payments are made each year.

Loan Payment Details

$0.00

Total Interest Paid

$0.00

Total Payments Made

$0.00

Loan Payoff Time

0 years, 0 months

How it's calculated: The monthly payment is determined using the standard loan amortization formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1], where P is the principal loan amount, i is the monthly interest rate (annual rate divided by 12), and n is the total number of payments (loan term in years multiplied by 12). Total interest is (Total Payments – Loan Amount).
Principal Paid Interest Paid
Payment # Date Payment Amount Principal Paid Interest Paid Remaining Balance
Amortization Schedule

What is an Amortize a Loan Calculator?

Understanding how loans work is crucial for sound financial planning. An amortize a loan calculator is a powerful, free online tool designed to demystify the repayment process of various types of loans. It allows you to input key loan details and instantly see how your payments are structured, how much interest you'll pay over time, and visualize the loan's progression toward full repayment. This type of calculator is indispensable for anyone taking out a mortgage, auto loan, personal loan, or any other form of debt where regular payments cover both principal and interest.

What is an Amortize a Loan Calculator?

An amortize a loan calculator, often referred to simply as an amortization calculator, is a financial tool that breaks down your loan payments over the life of the loan. It helps you understand the specific amounts of principal and interest that make up each payment. As you make payments, a portion goes towards reducing the outstanding loan balance (principal), and another portion covers the interest charged on that balance. An amortization calculator generates a detailed schedule showing this breakdown for every payment period, illustrating how the balance gradually decreases until it reaches zero.

Who should use it? Anyone who is:

  • Applying for a new loan (mortgage, auto, personal, student, business).
  • Considering refinancing an existing loan.
  • Evaluating different loan offers to compare terms and costs.
  • Looking to understand the financial impact of extra payments.
  • Planning their long-term budget and debt management strategy.

Common misconceptions about loan amortization:

  • Misconception: All loan payments are split equally between principal and interest. Reality: Early payments are heavily weighted towards interest, with principal reduction increasing over time.
  • Misconception: Interest is only calculated on the original loan amount. Reality: Interest is calculated on the *remaining principal balance* after each payment.
  • Misconception: Adding extra payments doesn't significantly shorten the loan term or reduce total interest. Reality: Even small extra payments, especially early on, can dramatically reduce the total interest paid and shorten the loan's life.

Amortize a Loan Calculator Formula and Mathematical Explanation

The core of an amortize a loan calculator lies in the standard loan amortization formula. This formula calculates the fixed periodic payment (M) required to fully repay a loan over a specified term, considering the principal amount, interest rate, and the number of payments.

The formula for calculating the periodic payment (M) is:

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

Where:

  • M = Periodic Payment (the amount you pay each period)
  • P = Principal Loan Amount (the initial amount borrowed)
  • i = Periodic Interest Rate (the annual interest rate divided by the number of payments per year)
  • n = Total Number of Payments (the loan term in years multiplied by the number of payments per year)

Variable Explanations and Table:

Variable Meaning Unit Typical Range
P (Principal) The total amount borrowed. Currency (e.g., $) $1,000 – $1,000,000+
Annual Interest Rate The yearly percentage charged by the lender. Percentage (%) 1% – 30%+
i (Periodic Rate) Annual Rate / Payments Per Year. Decimal (e.g., 0.05 / 12) Calculated
Loan Term (Years) The duration of the loan. Years 1 – 30+ years
Payments Per Year Frequency of payments (e.g., 12 for monthly). Integer 1, 2, 4, 12, 24, 26, 52
n (Total Payments) Loan Term (Years) * Payments Per Year. Count Calculated
M (Periodic Payment) The calculated fixed payment amount. Currency (e.g., $) Calculated
Total Interest Paid Sum of all interest portions over the loan's life. Currency (e.g., $) Calculated
Total Payments Sum of all payments made over the loan's life (M * n). Currency (e.g., $) Calculated

Once the periodic payment (M) is calculated, the amortization schedule is generated iteratively. For each payment period:

  1. Calculate the interest portion: Interest Paid = Remaining Balance * i
  2. Calculate the principal portion: Principal Paid = M – Interest Paid
  3. Update the remaining balance: New Balance = Remaining Balance – Principal Paid

This process repeats until the remaining balance is zero. An amortize a loan calculator automates this complex, repetitive calculation.

Practical Examples (Real-World Use Cases)

Let's explore how an amortize a loan calculator can be used in real-world scenarios.

Example 1: Purchasing a Home

Sarah is buying a house and needs a mortgage. She's looking at a loan offer with the following terms:

  • Loan Amount (P): $300,000
  • Annual Interest Rate: 6.5%
  • Loan Term: 30 years
  • Payments Per Year: 12 (Monthly)

Using the amortize a loan calculator:

  • Calculated Monthly Payment (M): ~$1,896.20
  • Total Interest Paid: ~$382,631.05
  • Total Payments Made: ~$682,631.05
  • Loan Payoff Time: 30 years, 0 months

Financial Interpretation: Sarah's monthly mortgage payment will be $1,896.20. Over the 30-year term, she will end up paying more in interest ($382,631.05) than the original loan amount. This highlights the significant long-term cost of borrowing for a home. She might consider making extra principal payments to reduce this interest burden, a scenario the calculator can also model if allowed.

Example 2: Buying a New Car

John is financing a new car. He has secured a loan with these details:

  • Loan Amount (P): $25,000
  • Annual Interest Rate: 7.0%
  • Loan Term: 5 years
  • Payments Per Year: 12 (Monthly)

Inputting these figures into the amortize a loan calculator yields:

  • Calculated Monthly Payment (M): ~$495.06
  • Total Interest Paid: ~$4,703.60
  • Total Payments Made: ~$29,703.60
  • Loan Payoff Time: 5 years, 0 months

Financial Interpretation: John's monthly car payment will be $495.06. Over five years, the total interest cost is substantial ($4,703.60) relative to the principal. This example shows how interest accrues even on shorter-term loans. Understanding this helps in deciding whether to pay more upfront or make larger monthly payments if feasible.

How to Use This Amortize a Loan Calculator

Our amortize a loan calculator is designed for simplicity and ease of use. Follow these steps:

  1. Enter Loan Amount: Input the total principal amount you are borrowing (e.g., $200,000 for a mortgage, $25,000 for a car).
  2. Input Annual Interest Rate: Enter the yearly interest rate as a percentage (e.g., 5 for 5%, 6.5 for 6.5%).
  3. Specify Loan Term: Enter the total duration of the loan in years (e.g., 30 years for a mortgage, 5 years for a car loan).
  4. Select Payment Frequency: Choose how often you will make payments per year (e.g., 12 for monthly, 4 for quarterly). This is crucial as it affects the periodic interest rate and the total number of payments.
  5. Click 'Calculate Loan': The calculator will instantly process your inputs.

How to Read Results:

  • Monthly Payment (Primary Result): This is the fixed amount you'll pay each period.
  • Total Interest Paid: The sum of all interest costs over the entire loan term.
  • Total Payments Made: The sum of all payments (Principal + Total Interest).
  • Loan Payoff Time: Confirms the loan is scheduled to be paid off within the term.
  • Amortization Schedule Table: Provides a detailed breakdown for each payment, showing how much goes to principal vs. interest and the remaining balance.
  • Amortization Chart: Visually represents the principal and interest paid over time.

Decision-Making Guidance: Use the calculator to compare different loan offers. If you're considering paying off a loan early, use the calculator to estimate potential savings. Even small additional payments can make a significant difference, as shown by advanced loan calculators. Understanding your amortization schedule empowers you to manage your debt more effectively and potentially save thousands of dollars in interest. This tool is a stepping stone to better [financial management](https://example.com/financial-management-guide). Remember to also explore [refinancing options](https://example.com/refinancing-guide) if market rates drop significantly.

Key Factors That Affect Amortize a Loan Results

Several factors significantly influence the outcomes of an amortize a loan calculator, impacting your payments, total interest, and loan duration.

1. Principal Loan Amount (P):

The most direct factor. A higher principal means larger payments, more interest charged over time, and potentially a longer repayment period if payments remain fixed. Reducing the principal upfront is key to minimizing long-term costs.

2. Annual Interest Rate (i):

A higher interest rate dramatically increases the cost of borrowing. Even a small percentage point increase can add thousands to the total interest paid, especially on long-term loans like mortgages. This is why [shopping for the best mortgage rates](https://example.com/mortgage-rates) is critical.

3. Loan Term (n):

A longer loan term generally results in lower periodic payments but significantly more total interest paid over the life of the loan. Conversely, a shorter term means higher payments but less total interest. Choosing the right term balances affordability with long-term cost.

4. Payment Frequency:

Making more frequent payments (e.g., bi-weekly instead of monthly) can slightly reduce the total interest paid and shorten the loan term. This is because you're making an extra full payment each year (26 bi-weekly payments = 13 monthly payments), which goes directly towards the principal.

5. Fees and Charges:

Loan origination fees, closing costs, prepayment penalties, and other associated fees are not always explicitly part of the basic amortization calculation but add to the overall cost of the loan. Always factor these into your total borrowing cost analysis.

6. Additional Payments:

Making extra payments towards the principal is one of the most effective ways to reduce the total interest paid and shorten the loan term. An amortize a loan calculator can help you see the impact of specific extra payment amounts.

7. Inflation and Economic Conditions:

While not directly in the calculator's formula, inflation can affect the *real* cost of your payments over time. Borrowing money when inflation is high can mean you're repaying the loan with dollars that are worth less than when you borrowed them. Conversely, rising interest rates can make existing variable-rate loans more expensive.

8. Tax Implications:

In some jurisdictions, the interest paid on certain loans (like mortgages) may be tax-deductible. This can reduce the effective cost of borrowing, though it doesn't change the amortization schedule itself. Consult a tax professional for specifics.

Frequently Asked Questions (FAQ)

Q1: What's the difference between principal and interest?

Principal is the original amount of money borrowed. Interest is the fee charged by the lender for the use of that money, calculated on the outstanding principal balance.

Q2: How does making extra principal payments affect my loan?

Extra principal payments reduce the outstanding balance faster. This means less interest accrues over time, and the loan will be paid off sooner. It's one of the most effective ways to save money on interest.

Q3: Can I use this calculator for any type of loan?

Yes, this calculator is suitable for most standard installment loans with fixed interest rates, including mortgages, auto loans, personal loans, and student loans. It may not be suitable for loans with variable interest rates or complex repayment structures.

Q4: What does "amortization" mean?

Amortization refers to the process of paying off a debt over time through regular installments. Each payment gradually reduces the principal balance until the loan is fully repaid.

Q5: Why is the interest portion of my payment higher at the beginning?

Interest is calculated based on the outstanding principal balance. At the start of the loan, the principal balance is at its highest, so a larger portion of your payment goes towards covering the interest. As the principal decreases, the interest portion of each subsequent payment also decreases.

Q6: What happens if I miss a payment?

Missing a payment typically incurs late fees and can negatively impact your credit score. Depending on the loan terms, interest may continue to accrue on the missed payment amount, potentially leading to a higher overall cost and longer repayment period. Always aim to make payments on time.

Q7: Can I use this calculator to see the effect of refinancing?

While this calculator focuses on a single loan scenario, you can use it to simulate new loan terms. For example, if you're considering refinancing a $200,000 loan at 7% for 30 years into a new loan at 5% for 30 years, you can input these new terms to see the potential savings.

Q8: How accurate are online amortization calculators?

Online calculators like this one are generally very accurate for standard, fixed-rate loans. They use well-established mathematical formulas. However, slight discrepancies may arise due to rounding methods used by different financial institutions or in cases of loans with irregular payment schedules or variable rates.

var loanAmountInput = document.getElementById('loanAmount'); var annualInterestRateInput = document.getElementById('annualInterestRate'); var loanTermYearsInput = document.getElementById('loanTermYears'); var paymentFrequencyInput = document.getElementById('paymentFrequency'); var loanAmountError = document.getElementById('loanAmountError'); var annualInterestRateError = document.getElementById('annualInterestRateError'); var loanTermYearsError = document.getElementById('loanTermYearsError'); var monthlyPaymentDisplay = document.getElementById('monthlyPayment'); var totalInterestDisplay = document.getElementById('totalInterest'); var totalPaymentsDisplay = document.getElementById('totalPayments'); var loanPayoffTimeDisplay = document.getElementById('loanPayoffTime'); var amortizationScheduleBody = document.getElementById('amortizationScheduleBody'); var tableCaption = document.getElementById('tableCaption'); var chartCanvas = document.getElementById('amortizationChart'); var chartContext = chartCanvas.getContext('2d'); var loanChartInstance = null; // To hold the chart instance function formatCurrency(amount) { return '$' + amount.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,'); } function formatLoanPayoffTime(totalMonths) { var years = Math.floor(totalMonths / 12); var months = totalMonths % 12; return years + ' years, ' + months + ' months'; } function validateInput(input, errorElement, min, max, name) { var value = parseFloat(input.value); var isValid = true; errorElement.style.display = 'none'; // Hide error by default if (isNaN(value)) { errorElement.textContent = name + ' must be a number.'; errorElement.style.display = 'block'; isValid = false; } else if (value max) { errorElement.textContent = name + ' cannot be greater than ' + formatCurrency(max) + '.'; errorElement.style.display = 'block'; isValid = false; } if (isValid && value === 0 && name !== 'Loan Amount ($)') { // Allow 0 for some fields if sensible, but not loan amount itself unless it's a free item. // Specifically for interest rate and term, 0 is not usually practical if (name === 'Annual Interest Rate (%)' || name === 'Loan Term (Years)') { errorElement.textContent = name + ' cannot be zero.'; errorElement.style.display = 'block'; isValid = false; } } return isValid; } function calculateAmortization() { // Reset errors loanAmountError.style.display = 'none'; annualInterestRateError.style.display = 'none'; loanTermYearsError.style.display = 'none'; // Validate inputs var isValidLoanAmount = validateInput(loanAmountInput, loanAmountError, 0, null, 'Loan Amount ($)'); var isValidAnnualInterestRate = validateInput(annualInterestRateInput, annualInterestRateError, 0, 100, 'Annual Interest Rate (%)'); var isValidLoanTermYears = validateInput(loanTermYearsInput, loanTermYearsError, 1, null, 'Loan Term (Years)'); if (!isValidLoanAmount || !isValidAnnualInterestRate || !isValidLoanTermYears) { return; // Stop calculation if validation fails } var principal = parseFloat(loanAmountInput.value); var annualRate = parseFloat(annualInterestRateInput.value); var years = parseInt(loanTermYearsInput.value); var frequency = parseInt(paymentFrequencyInput.value); if (principal 0) { monthlyPayment = principal * (monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) / (Math.pow(1 + monthlyRate, numberOfPayments) – 1); } else { monthlyPayment = principal / numberOfPayments; // Simple division if rate is 0 } var totalPayments = monthlyPayment * numberOfPayments; var totalInterest = totalPayments – principal; monthlyPaymentDisplay.textContent = formatCurrency(monthlyPayment); totalInterestDisplay.textContent = formatCurrency(totalInterest); totalPaymentsDisplay.textContent = formatCurrency(totalPayments); loanPayoffTimeDisplay.textContent = formatLoanPayoffTime(numberOfPayments); // Update table caption to reflect loan amount and rate for clarity tableCaption.textContent = 'Amortization Schedule for a Loan of ' + formatCurrency(principal) + ' at ' + annualRate.toFixed(2) + '% over ' + years + ' years'; // Generate Amortization Schedule amortizationScheduleBody.innerHTML = "; // Clear previous schedule var remainingBalance = principal; var principalPaidTotal = 0; var interestPaidTotal = 0; var paymentDates = []; var principalSeries = []; var interestSeries = []; var currentDate = new Date(); // Start date for schedule for (var i = 0; i < numberOfPayments; i++) { var paymentRow = amortizationScheduleBody.insertRow(); var interestPayment = remainingBalance * monthlyRate; var principalPayment = monthlyPayment – interestPayment; // Adjust for final payment to avoid rounding errors if (i === numberOfPayments – 1) { principalPayment = remainingBalance; monthlyPayment = interestPayment + principalPayment; // Recalculate exact final payment totalPayments = principal + totalInterest; // Recalculate exact total payments } remainingBalance -= principalPayment; if (remainingBalance < 0.01) remainingBalance = 0; // Prevent tiny negative balances due to rounding principalPaidTotal += principalPayment; interestPaidTotal += interestPayment; paymentDates.push(i + 1); // Payment number principalSeries.push(principalPayment); interestSeries.push(interestPayment); var date = new Date(currentDate); // Add months based on frequency for a more realistic date progression if (frequency === 12) date.setMonth(date.getMonth() + 1); else if (frequency === 4) date.setMonth(date.getMonth() + 3); else if (frequency === 2) date.setMonth(date.getMonth() + 6); else date.setFullYear(date.getFullYear() + 1); currentDate = date; // Update for next iteration paymentRow.insertCell(0).textContent = (i + 1); paymentRow.insertCell(1).textContent = date.toISOString().slice(0, 10); // YYYY-MM-DD format paymentRow.insertCell(2).textContent = formatCurrency(monthlyPayment); paymentRow.insertCell(3).textContent = formatCurrency(principalPayment); paymentRow.insertCell(4).textContent = formatCurrency(interestPayment); paymentRow.insertCell(5).textContent = formatCurrency(remainingBalance); } // Update totals displays with potentially adjusted final values totalInterestDisplay.textContent = formatCurrency(interestPaidTotal); totalPaymentsDisplay.textContent = formatCurrency(principal + interestPaidTotal); updateChart(paymentDates, principalSeries, interestSeries); } function updateChart(labels, principalData, interestData) { if (loanChartInstance) { loanChartInstance.destroy(); // Destroy previous chart instance } chartContext.clearRect(0, 0, chartCanvas.width, chartCanvas.height); // Clear canvas // Resize canvas to fit container if necessary, maintaining aspect ratio. // For simplicity here, assuming fixed size or responsive CSS handles it. // In a real-world scenario, you'd handle resize events. if (labels.length === 0) return; // Don't draw if no data // Create a new chart instance loanChartInstance = new Chart(chartContext, { type: 'bar', // Changed to bar for better comparison of principal/interest per payment data: { labels: labels, datasets: [{ label: 'Principal Paid', data: principalData, backgroundColor: 'rgba(54, 162, 235, 0.6)', // Blue borderColor: 'rgba(54, 162, 235, 1)', borderWidth: 1, stack: 'Payments' // Stack payments together }, { label: 'Interest Paid', data: interestData, backgroundColor: 'rgba(255, 99, 132, 0.6)', // Red borderColor: 'rgba(255, 99, 132, 1)', borderWidth: 1, stack: 'Payments' // Stack payments together }] }, options: { responsive: true, maintainAspectRatio: true, // Set to true if you want aspect ratio to be maintained scales: { x: { title: { display: true, text: 'Payment Number' }, stacked: true, // Stack bars on x-axis }, y: { title: { display: true, text: 'Amount ($)' }, stacked: true, // Stack bars on y-axis beginAtZero: true } }, plugins: { title: { display: true, text: 'Principal vs. Interest Paid Per Payment' }, tooltip: { callbacks: { label: function(context) { var label = context.dataset.label || ''; if (label) { label += ': '; } if (context.parsed.y !== null) { label += formatCurrency(context.parsed.y); } return label; } } } } } }); } function resetForm() { loanAmountInput.value = '200000'; annualInterestRateInput.value = '5'; loanTermYearsInput.value = '30'; paymentFrequencyInput.value = '12'; // Clear errors loanAmountError.style.display = 'none'; annualInterestRateError.style.display = 'none'; loanTermYearsError.style.display = 'none'; calculateAmortization(); // Recalculate with default values } function copyResults() { var principal = parseFloat(loanAmountInput.value); var annualRate = parseFloat(annualInterestRateInput.value); var years = parseInt(loanTermYearsInput.value); var frequency = parseInt(paymentFrequencyInput.value); var monthlyPayment = monthlyPaymentDisplay.textContent; var totalInterest = totalInterestDisplay.textContent; var totalPayments = totalPaymentsDisplay.textContent; var payoffTime = loanPayoffTimeDisplay.textContent; var assumptions = "Loan Amount: " + formatCurrency(principal) + "\n"; assumptions += "Annual Interest Rate: " + annualRate.toFixed(2) + "%\n"; assumptions += "Loan Term: " + years + " years (" + (years * frequency) + " payments)\n"; assumptions += "Payment Frequency: " + paymentFrequencyInput.options[paymentFrequencyInput.selectedIndex].text + "\n\n"; var resultsText = "— Loan Amortization Summary —\n\n"; resultsText += "Key Assumptions:\n" + assumptions; resultsText += "Monthly Payment: " + monthlyPayment + "\n"; resultsText += "Total Interest Paid: " + totalInterest + "\n"; resultsText += "Total Payments Made: " + totalPayments + "\n"; resultsText += "Loan Payoff Time: " + payoffTime + "\n\n"; resultsText += "— Amortization Schedule (First 5 Rows) —\n"; var scheduleRows = amortizationScheduleBody.getElementsByTagName('tr'); var limit = Math.min(scheduleRows.length, 5); // Copy first 5 rows for(var i=0; i 5) resultsText += "…\n"; // Use the modern Clipboard API if available if (navigator.clipboard && window.isSecureContext) { navigator.clipboard.writeText(resultsText).then(function() { // Optionally show a success message to the user alert('Results copied to clipboard!'); }).catch(function(err) { console.error('Failed to copy text: ', err); // Fallback to older method if Clipboard API fails copyToClipboardFallback(resultsText); }); } else { // Fallback for older browsers or insecure contexts copyToClipboardFallback(resultsText); } } // Fallback method for copying text function copyToClipboardFallback(text) { var textArea = document.createElement("textarea"); textArea.value = text; // Make the textarea out of viewport textArea.style.position = "fixed"; textArea.style.left = "-9999px"; textArea.style.top = "-9999px"; document.body.appendChild(textArea); textArea.focus(); textArea.select(); try { var successful = document.execCommand('copy'); var msg = successful ? 'successful' : 'unsuccessful'; alert('Results copied to clipboard (' + msg + ')!'); } catch (err) { alert('Oops, unable to copy'); } document.body.removeChild(textArea); } // Initial calculation on page load window.onload = function() { calculateAmortization(); // Add Chart.js library dynamically if needed, or ensure it's included in the HTML // For this example, assume Chart.js is available globally or included via CDN // If not, you'd need to add: in the // IMPORTANT: Ensure Chart.js is loaded BEFORE this script runs. // For a self-contained HTML, it's best to include it directly. // Let's add it dynamically here for demonstration if not found if (typeof Chart === 'undefined') { var script = document.createElement('script'); script.src = 'https://cdn.jsdelivr.net/npm/chart.js'; script.onload = function() { console.log("Chart.js loaded dynamically."); // Recalculate if chart was needed immediately calculateAmortization(); }; document.head.appendChild(script); } };

Leave a Comment