Estimate your monthly mortgage payments accurately.
Loan Repayment Calculator
Enter the total amount you wish to borrow.
Enter the yearly interest rate for your loan.
Enter the total duration of the loan in years.
Your Estimated Monthly Repayment
$0.00
0.00
Total Interest
0.00
Total Paid
0.00
Principal
The monthly repayment is calculated using the standard mortgage payment 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 (loan term in months).
Loan Amortization Schedule (First 12 Months)
Month
Starting Balance
Payment
Interest Paid
Principal Paid
Ending Balance
Summary of your loan's first year payments.
Loan Repayment Breakdown (First 12 Months)
Visual representation of principal vs. interest paid over the first year.
Home Loan Repayments Calculator: Understanding Your Mortgage Costs
What is a Home Loan Repayments Calculator?
A home loan repayments calculator is a vital online tool designed to help individuals estimate the monthly payments required for a mortgage. It simplifies complex financial calculations, allowing prospective homeowners to understand the financial commitment involved in purchasing a property. By inputting key variables such as the loan amount, annual interest rate, and loan term, the calculator provides an immediate estimate of the principal and interest payments you can expect to make each month. This tool is indispensable for budgeting, financial planning, and comparing different loan offers. It demystifies the often-daunting process of securing a home loan, making it more accessible and understandable for everyone, regardless of their financial expertise. The primary goal of a home loan repayments calculator is to provide clarity and control over your mortgage finances.
Who should use it: Anyone considering buying a home, refinancing an existing mortgage, or simply wanting to understand the cost of homeownership. First-time homebuyers will find it particularly useful for getting a realistic sense of affordability. Investors looking to purchase rental properties also benefit from using this calculator to assess potential returns and expenses. Essentially, if a home loan is part of your financial future, this calculator is for you.
Common misconceptions: Many people believe the monthly payment is fixed for the entire loan term, which is true for fixed-rate mortgages but not for adjustable-rate mortgages (ARMs). Another misconception is that the calculator only shows the principal and interest; often, property taxes, homeowner's insurance, and private mortgage insurance (PMI) are added to the total monthly housing cost, which this calculator doesn't include by default but are crucial considerations. Some also underestimate the total amount of interest paid over the life of a long-term loan, a detail the home loan repayments calculator helps to illuminate.
Home Loan Repayments Calculator Formula and Mathematical Explanation
The home loan repayments calculator uses the standard annuity formula for calculating loan payments. This formula determines the fixed periodic payment required to fully amortize a loan over a specified period. The formula ensures that each payment covers both the interest accrued since the last payment and a portion of the principal balance.
The formula is:
M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1]
Where:
Variable
Meaning
Unit
Typical Range
M
Monthly Payment
Currency ($)
Varies based on loan details
P
Principal Loan Amount
Currency ($)
$50,000 – $1,000,000+
i
Monthly Interest Rate
Decimal (Rate / 12 / 100)
0.003 – 0.015 (for 3.6% – 18% APR)
n
Total Number of Payments
Months
60 – 360 (5 – 30 years)
Mathematical Derivation: The formula is derived from the present value of an ordinary annuity. It equates the principal loan amount (P) to the sum of the present values of all future monthly payments (M). Each payment M is discounted back to its present value. Solving this equation for M yields the formula above. The monthly interest rate 'i' is calculated by dividing the annual interest rate by 12 (for the number of months in a year), and then dividing by 100 to convert the percentage to a decimal. The total number of payments 'n' is calculated by multiplying the loan term in years by 12.
For example, if P = $300,000, Annual Rate = 5.5%, and Term = 30 years:
Sarah is a first-time homebuyer looking at a property priced at $400,000. She has a down payment saved, so she needs to borrow $350,000. She has secured a pre-approval for a 30-year mortgage with an annual interest rate of 6.2%. Sarah uses the home loan repayments calculator:
Loan Amount: $350,000
Annual Interest Rate: 6.2%
Loan Term: 30 Years
The calculator outputs:
Monthly Repayment: Approximately $2,150.68
Total Interest Paid: Approximately $424,245.57
Total Repayment: Approximately $774,245.57
Financial Interpretation: Sarah understands that while her principal loan is $350,000, she will end up paying significantly more over the 30 years due to interest. This helps her assess if the monthly payment fits her budget and consider options like making extra principal payments to reduce total interest paid. This crucial insight from the home loan repayments calculator informs her decision-making.
Example 2: Refinancing a Mortgage
John and Mary currently have a $200,000 balance remaining on their 15-year mortgage, taken out 5 years ago. Their current interest rate is 7.5%. They see that current market rates have dropped, and they are offered a new 10-year mortgage for the remaining balance at 5.5% annual interest.
Financial Interpretation: By refinancing, they can lower their monthly payment by about $235, saving them substantial money over the next 10 years. The home loan repayments calculator clearly shows the financial benefit of refinancing, helping them decide to proceed.
Enter Loan Amount: Input the total principal amount you intend to borrow for your home purchase.
Input Annual Interest Rate: Enter the annual interest rate (APR) offered by the lender. Ensure you are using the correct percentage.
Specify Loan Term: Enter the total duration of the loan in years (e.g., 15, 20, 30 years).
Click 'Calculate': Press the calculate button. The calculator will instantly display your estimated monthly repayment.
How to read results:
Monthly Repayment: This is the primary figure showing your estimated fixed monthly cost for principal and interest.
Total Interest Paid: This cumulative figure shows how much you'll pay in interest over the entire loan term.
Total Repayment: This is the sum of the original loan amount and all the interest paid over the loan's life.
Principal Portion: In the first year breakdown, this shows how much of your early payments goes directly towards reducing the loan balance.
Decision-making guidance: Use the results to assess affordability. If the monthly payment is too high, consider a lower-priced home, a larger down payment, a shorter loan term, or negotiating a better interest rate. The calculator is also useful for comparing different loan offers side-by-side. Always remember to factor in additional costs like property taxes, insurance, and potential HOA fees, which are not included in this basic home loan repayments calculator but are essential for your overall housing budget.
Key Factors That Affect Home Loan Repayment Results
Several crucial factors influence the monthly payments calculated by a home loan repayments calculator and the overall cost of your mortgage:
Loan Amount (Principal): The most direct factor. A larger loan amount naturally results in higher monthly payments and a greater total amount repaid. This is the 'P' in our formula.
Annual Interest Rate (APR): Even small differences in the interest rate can have a significant impact over the life of a long-term loan. A higher APR means more interest paid each month, increasing your payment and total cost. This is 'i' in the formula.
Loan Term (Years): A longer loan term (e.g., 30 years vs. 15 years) reduces your monthly payment but significantly increases the total interest paid over time. Conversely, a shorter term means higher monthly payments but less total interest. This determines 'n' in the formula.
Down Payment Size: While not directly in the monthly payment formula, your down payment affects the loan amount (P). A larger down payment reduces P, thus lowering monthly payments and the total interest paid.
Loan Type (Fixed vs. Adjustable): This calculator primarily models fixed-rate loans. Adjustable-rate mortgages (ARMs) have initial rates that may be lower but can increase or decrease over time, making future payments unpredictable.
Fees and Closing Costs: Lenders often charge various fees (origination fees, appraisal fees, etc.) in addition to interest. While not part of the direct repayment calculation, these add to the overall cost of obtaining the loan. Ensure you understand all associated costs.
Credit Score: Your credit score heavily influences the interest rate you are offered. A higher credit score typically qualifies you for lower interest rates, reducing your monthly payment and total interest paid.
Inflation and Economic Conditions: While not directly calculated, broader economic factors like inflation can influence interest rate trends. Lenders adjust rates based on market conditions and inflation expectations.
Frequently Asked Questions (FAQ)
What is the difference between principal and interest in my payment?
Your monthly mortgage payment is typically split between paying down the principal loan balance and covering the interest charged by the lender. In the early years of a loan, a larger portion of your payment goes towards interest. As the loan matures, more of your payment is applied to the principal.
Does the calculator include property taxes and insurance?
No, this home loan repayments calculator calculates only the principal and interest (P&I) portion of your mortgage payment. Property taxes, homeowner's insurance, and potentially Private Mortgage Insurance (PMI) or HOA fees are additional costs that you will need to budget for separately. These are often bundled into an "escrow" payment.
What happens if I make extra payments?
Making extra payments towards your principal can significantly reduce the total interest paid over the life of the loan and allow you to pay off your mortgage faster. Many lenders allow extra principal payments without penalty. Check with your lender for specifics.
Is a 15-year or 30-year mortgage better?
A 15-year mortgage typically has a lower interest rate and results in paying much less interest over time. However, the monthly payments are higher. A 30-year mortgage offers lower monthly payments, making it more affordable on a month-to-month basis, but you'll pay significantly more interest over the loan's duration. The best choice depends on your financial situation and goals.
How does my credit score affect my home loan repayment?
Your credit score is a primary factor lenders use to determine your interest rate. A higher credit score generally qualifies you for lower interest rates, which directly reduces your monthly home loan repayments and the total amount of interest you pay over the loan's life.
What is an amortization schedule?
An amortization schedule is a table that outlines each payment on a loan. It details how much of each payment goes towards interest and principal, and the remaining balance after each payment. Our calculator provides a sample schedule to illustrate this.
Can I use this calculator for investment properties?
Yes, you can use this home loan repayments calculator to estimate loan costs for investment properties. However, remember that investment property loans may have different interest rates, terms, and requirements than owner-occupied home loans.
What is the difference between APR and interest rate?
The interest rate is the cost of borrowing money, expressed as a percentage. The Annual Percentage Rate (APR) is a broader measure of the cost of borrowing money, including not only the interest rate but also certain fees and other charges associated with the loan. APR provides a more accurate picture of the total cost of a loan.
Learn about factors that influence mortgage interest rates and how they work.
var loanAmountInput = document.getElementById("loanAmount");
var annualInterestRateInput = document.getElementById("annualInterestRate");
var loanTermYearsInput = document.getElementById("loanTermYears");
var monthlyRepaymentSpan = document.getElementById("monthlyRepayment");
var totalInterestPaidSpan = document.getElementById("totalInterestPaid");
var totalRepaymentSpan = document.getElementById("totalRepayment");
var principalPortionSpan = document.getElementById("principalPortion");
var amortizationTableBody = document.getElementById("amortizationTableBody");
var repaymentChartCanvas = document.getElementById("repaymentChart");
var chartInstance = null; // To hold the chart instance
function formatCurrency(amount) {
return "$" + amount.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
}
function formatRate(rate) {
return rate.toFixed(2) + "%";
}
function calculateRepayments() {
// Clear previous errors
document.getElementById("loanAmountError").style.display = "none";
document.getElementById("annualInterestRateError").style.display = "none";
document.getElementById("loanTermYearsError").style.display = "none";
var loanAmount = parseFloat(loanAmountInput.value);
var annualInterestRate = parseFloat(annualInterestRateInput.value);
var loanTermYears = parseInt(loanTermYearsInput.value);
var loanAmountError = document.getElementById("loanAmountError");
var annualInterestRateError = document.getElementById("annualInterestRateError");
var loanTermYearsError = document.getElementById("loanTermYearsError");
var isValid = true;
if (isNaN(loanAmount) || loanAmount <= 0) {
loanAmountError.textContent = "Please enter a valid loan amount greater than zero.";
loanAmountError.style.display = "block";
isValid = false;
}
if (isNaN(annualInterestRate) || annualInterestRate 100) {
annualInterestRateError.textContent = "Please enter a valid interest rate between 0% and 100%.";
annualInterestRateError.style.display = "block";
isValid = false;
}
if (isNaN(loanTermYears) || loanTermYears 0) {
monthlyRepayment = loanAmount * (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments)) / (Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1);
} else {
monthlyRepayment = loanAmount / numberOfPayments; // Simple division if interest rate is 0
}
var totalRepayment = monthlyRepayment * numberOfPayments;
var totalInterestPaid = totalRepayment – loanAmount;
var principalPaidFirstYear = 0;
monthlyRepaymentSpan.textContent = formatCurrency(monthlyRepayment);
totalInterestPaidSpan.textContent = formatCurrency(totalInterestPaid);
totalRepaymentSpan.textContent = formatCurrency(totalRepayment);
// The "Principal" shown here is the total principal of the loan, not just first year.
// For clarity and consistency with total repayment, we display the original loan amount.
principalPortionSpan.textContent = formatCurrency(loanAmount);
// Generate Amortization Table (First 12 Months)
amortizationTableBody.innerHTML = ""; // Clear existing table rows
var currentBalance = loanAmount;
var principalPaidTotal = 0;
var interestPaidTotal = 0;
var monthlyPaymentForTable = monthlyRepayment;
for (var i = 0; i < Math.min(12, numberOfPayments); i++) {
var interestPayment = currentBalance * monthlyInterestRate;
var principalPayment = monthlyPaymentForTable – interestPayment;
// Handle potential rounding issues for the last payment
if (currentBalance – principalPayment < 0) {
principalPayment = currentBalance;
monthlyPaymentForTable = principalPayment + interestPayment; // Adjust monthly payment if needed
}
principalPaidTotal += principalPayment;
interestPaidTotal += interestPayment;
currentBalance -= principalPayment;
var row = amortizationTableBody.insertRow();
row.insertCell(0).textContent = (i + 1);
row.insertCell(1).textContent = formatCurrency(currentBalance + principalPayment); // Starting balance for this month
row.insertCell(2).textContent = formatCurrency(monthlyPaymentForTable);
row.insertCell(3).textContent = formatCurrency(interestPayment);
row.insertCell(4).textContent = formatCurrency(principalPayment);
row.insertCell(5).textContent = formatCurrency(currentBalance);
}
// Update the 'Principal Paid' span to reflect the first year principal for context
// Note: This might be confusing. Let's keep the original display of total principal.
// The table shows breakdown. We will add a note in chart legend.
updateChart(monthlyRepayment, interestPaidTotal, principalPaidTotal, monthlyInterestRate, numberOfPayments);
}
function resetResults() {
monthlyRepaymentSpan.textContent = "$0.00";
totalInterestPaidSpan.textContent = "$0.00";
totalRepaymentSpan.textContent = "$0.00";
principalPortionSpan.textContent = "$0.00";
amortizationTableBody.innerHTML = "";
if (chartInstance) {
chartInstance.destroy();
chartInstance = null;
}
}
function resetCalculator() {
loanAmountInput.value = "300000";
annualInterestRateInput.value = "5.5";
loanTermYearsInput.value = "30";
calculateRepayments();
}
function copyResults() {
var monthlyRepayment = monthlyRepaymentSpan.textContent;
var totalInterestPaid = totalInterestPaidSpan.textContent;
var totalRepayment = totalRepaymentSpan.textContent;
var principalLoanAmount = formatCurrency(parseFloat(loanAmountInput.value));
var annualRate = formatRate(parseFloat(annualInterestRateInput.value));
var loanTerm = loanTermYearsInput.value + " years";
var assumptions = "Key Assumptions:\n";
assumptions += "- Loan Amount: " + principalLoanAmount + "\n";
assumptions += "- Annual Interest Rate: " + annualRate + "\n";
assumptions += "- Loan Term: " + loanTerm + "\n";
var textToCopy = "Home Loan Repayment Estimates:\n\n";
textToCopy += "Estimated Monthly Repayment (P&I): " + monthlyRepayment + "\n";
textToCopy += "Total Interest Paid Over Loan Term: " + totalInterestPaid + "\n";
textToCopy += "Total Amount Paid (Principal + Interest): " + totalRepayment + "\n\n";
textToCopy += assumptions;
// Use navigator.clipboard for modern browsers
navigator.clipboard.writeText(textToCopy).then(function() {
// Optionally provide user feedback, e.g., a temporary message
var copyButton = document.querySelector('.copy-button');
var originalText = copyButton.textContent;
copyButton.textContent = 'Copied!';
setTimeout(function() {
copyButton.textContent = originalText;
}, 2000);
}).catch(function(err) {
console.error('Failed to copy text: ', err);
// Fallback for older browsers or if permission denied
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 ? 'Copied!' : 'Copy failed';
var copyButton = document.querySelector('.copy-button');
var originalText = copyButton.textContent;
copyButton.textContent = msg;
setTimeout(function() {
copyButton.textContent = originalText;
}, 2000);
} catch (err) {
console.error('Fallback: Oops, unable to copy', err);
var copyButton = document.querySelector('.copy-button');
var originalText = copyButton.textContent;
copyButton.textContent = 'Copy Failed';
setTimeout(function() {
copyButton.textContent = originalText;
}, 2000);
}
document.body.removeChild(textArea);
});
}
function updateChart(monthlyPayment, totalInterestFirstYear, totalPrincipalFirstYear, monthlyInterestRate, numberOfPayments) {
if (repaymentChartCanvas.getContext) {
var ctx = repaymentChartCanvas.getContext('2d');
// Destroy previous chart instance if it exists
if (chartInstance) {
chartInstance.destroy();
}
// Calculate total principal and interest for the *entire* loan term for context in legend,
// but plot only the first year data.
var totalLoanAmount = parseFloat(loanAmountInput.value);
var totalLoanTermMonths = parseInt(loanTermYearsInput.value) * 12;
var totalLoanInterest = 0;
var currentBalanceForTotalCalc = totalLoanAmount;
var monthlyInterestRateForTotalCalc = parseFloat(annualInterestRateInput.value) / 100 / 12;
var monthlyPaymentForTotalCalc = monthlyPayment; // Use the calculated monthly payment
// Handle zero interest rate case for total interest calculation
if (monthlyInterestRateForTotalCalc === 0) {
totalLoanInterest = 0;
} else {
for (var i = 0; i < totalLoanTermMonths; i++) {
var interestPayment = currentBalanceForTotalCalc * monthlyInterestRateForTotalCalc;
var principalPayment = monthlyPaymentForTotalCalc – interestPayment;
// Adjust for last payment if it overpays
if (currentBalanceForTotalCalc – principalPayment < 0) {
principalPayment = currentBalanceForTotalCalc;
}
totalLoanInterest += interestPayment;
currentBalanceForTotalCalc -= principalPayment;
if (currentBalanceForTotalCalc <= 0) break; // Loan fully paid
}
}
var totalLoanInterestFormatted = formatCurrency(totalLoanInterest);
// Data for the chart (first 12 months)
var labels = [];
var interestData = [];
var principalData = [];
var currentBalance = totalLoanAmount;
var principalPaidThisYear = 0;
var interestPaidThisYear = 0;
for (var i = 0; i < Math.min(12, totalLoanTermMonths); i++) {
labels.push("Month " + (i + 1));
var interestPayment = currentBalance * monthlyInterestRate;
var principalPayment = monthlyPayment – interestPayment;
// Ensure we don't overpay the principal in the last month of the loan
if (currentBalance – principalPayment < 0) {
principalPayment = currentBalance;
// Adjust monthly payment if it was the last payment
// monthlyPayment = principalPayment + interestPayment;
}
interestData.push(interestPayment);
principalData.push(principalPayment);
currentBalance -= principalPayment;
principalPaidThisYear += principalPayment;
interestPaidThisYear += interestPayment;
}
chartInstance = new Chart(ctx, {
type: 'bar', // Changed to bar for better comparison of parts
data: {
labels: labels,
datasets: [{
label: 'Interest Paid',
data: interestData,
backgroundColor: 'rgba(255, 99, 132, 0.6)', // Reddish
borderColor: 'rgba(255, 99, 132, 1)',
borderWidth: 1,
type: 'line' // Optional: overlay as line
}, {
label: 'Principal Paid',
data: principalData,
backgroundColor: 'rgba(54, 162, 235, 0.6)', // Bluish
borderColor: 'rgba(54, 162, 235, 1)',
borderWidth: 1
}]
},
options: {
responsive: true,
maintainAspectRatio: false,
scales: {
y: {
beginAtZero: true,
title: {
display: true,
text: 'Amount ($)'
},
ticks: {
callback: function(value) {
return formatCurrency(value);
}
}
},
x: {
title: {
display: true,
text: 'Loan Period'
}
}
},
plugins: {
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;
}
}
},
legend: {
position: 'top',
labels: {
// Append total interest to legend item
generateLabels: function(chart) {
var originalLabels = Chart.defaults.plugins.legend.labels.generateLabels(chart);
originalLabels.forEach(function(label) {
if (label.text === 'Interest Paid') {
label.text = 'Interest Paid (Total Loan: ' + totalLoanInterestFormatted + ')';
} else if (label.text === 'Principal Paid') {
label.text = 'Principal Paid (First Year)';
}
});
return originalLabels;
}
}
}
}
}
});
}
}
// Function to toggle FAQ answers
function toggleFaq(element) {
var faqItem = element.closest('.faq-item');
faqItem.classList.toggle('open');
var answer = faqItem.querySelector('.answer');
if (answer.style.display === "block") {
answer.style.display = "none";
} else {
answer.style.display = "block";
}
}
// Initial calculation on page load
document.addEventListener("DOMContentLoaded", function() {
// Ensure chart canvas exists before trying to update it
if (repaymentChartCanvas) {
// Need to load Chart.js library for canvas
// For this example, we are using pure canvas API, so no external library needed.
// However, for more complex charts, Chart.js would be ideal.
// Since the prompt explicitly forbids external libraries, we will simulate chart drawing if needed.
// For now, we assume canvas drawing will be implemented directly or is not strictly required beyond the placeholder.
// If actual drawing is needed, a pure JS drawing approach would be complex for bars/lines.
// Given the constraint, we'll focus on the structure and assume a simple visualization logic or rely on a hypothetical Chart.js if it were allowed.
// *** REVISITING: The prompt stated "Native OR Pure SVG".
// Let's stick to HTML/JS DOM manipulation for now.
// Re-implementing the chart logic using pure Canvas API for drawing shapes.
// This can get complex quickly for bar/line charts.
// Let's re-evaluate. The simplest interpretation is that the canvas element is present,
// and a chart *would* be drawn. For a production-ready example WITHOUT external libs,
// drawing a dynamic multi-series bar/line chart is VERY involved.
// I will proceed with the Chart.js structure as a placeholder logic, assuming
// a library *could* be used if not for the constraint, and focus on the data preparation.
// If pure canvas is mandatory and complex, it significantly increases the scope.
// FOR NOW: I'm structuring it AS IF Chart.js was used, as per common practice,
// but will keep it commented or use dummy drawing if strictly required.
// Since Chart.js is forbidden, I will add a note that drawing is complex and focus on data structure.
// *** UPDATE: I will attempt to draw a simple bar chart using Canvas API for Principal vs Interest.
// This will be rudimentary.
updateChart([], [], [], 0, 0); // Call to initialize canvas placeholder if needed
}
calculateRepayments(); // Perform initial calculation
});
// Adding event listeners for input changes to trigger recalculation in real-time
loanAmountInput.addEventListener("input", calculateRepayments);
annualInterestRateInput.addEventListener("input", calculateRepayments);
loanTermYearsInput.addEventListener("input", calculateRepayments);
// — Canvas Drawing Logic (Simplified, rudimentary) —
// This part is complex without libraries. This is a basic illustration.
function updateChart(monthlyPayment, totalInterestFirstYear, totalPrincipalFirstYear, monthlyInterestRate, numberOfPayments) {
if (!repaymentChartCanvas || !repaymentChartCanvas.getContext) {
console.log("Canvas not supported or element not found.");
return;
}
var ctx = repaymentChartCanvas.getContext('2d');
ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height); // Clear previous drawings
var data = {
labels: [],
principal: [],
interest: []
};
var totalLoanAmount = parseFloat(loanAmountInput.value);
var annualInterestRate = parseFloat(annualInterestRateInput.value);
var loanTermYears = parseInt(loanTermYearsInput.value);
var monthlyInterestRateCalc = annualInterestRate / 100 / 12;
var numPayments = loanTermYears * 12;
var monthlyPaymentCalc = 0;
if (monthlyInterestRateCalc > 0) {
monthlyPaymentCalc = totalLoanAmount * (monthlyInterestRateCalc * Math.pow(1 + monthlyInterestRateCalc, numPayments)) / (Math.pow(1 + monthlyInterestRateCalc, numPayments) – 1);
} else {
monthlyPaymentCalc = totalLoanAmount / numPayments;
}
var currentBalance = totalLoanAmount;
for (var i = 0; i < Math.min(12, numPayments); i++) {
data.labels.push("Month " + (i + 1));
var interestPayment = currentBalance * monthlyInterestRateCalc;
var principalPayment = monthlyPaymentCalc – interestPayment;
if (currentBalance – principalPayment < 0) {
principalPayment = currentBalance;
}
data.interest.push(interestPayment);
data.principal.push(principalPayment);
currentBalance -= principalPayment;
}
if (data.labels.length === 0) return; // No data to draw
var canvasWidth = ctx.canvas.width;
var canvasHeight = ctx.canvas.height;
var barWidth = (canvasWidth * 0.8) / data.labels.length * 0.4; // Width for each bar type
var gapBetweenBars = barWidth * 0.2;
var gapBetweenSets = (canvasWidth * 0.8) / data.labels.length * 0.4; // Gap between month sets
var maxValue = Math.max.apply(null, data.principal.concat(data.interest));
var scaleY = (canvasHeight * 0.8) / maxValue; // Scale factor for Y axis
ctx.font = "12px Arial";
ctx.textAlign = "center";
// Draw Axes and Labels
ctx.beginPath();
ctx.moveTo(canvasWidth * 0.1, canvasHeight * 0.9); // Y axis start
ctx.lineTo(canvasWidth * 0.1, canvasHeight * 0.1); // Y axis end
ctx.lineTo(canvasWidth * 0.9, canvasHeight * 0.9); // X axis end
ctx.strokeStyle = '#ccc';
ctx.stroke();
// Y-axis labels
var numYLabels = 5;
for (var i = 0; i <= numYLabels; i++) {
var labelValue = Math.round(maxValue / numYLabels * i);
var yPos = canvasHeight * 0.9 – (labelValue * scaleY);
ctx.fillText(formatCurrency(labelValue), canvasWidth * 0.08, yPos);
}
// Draw Bars
var startX = canvasWidth * 0.15;
for (var i = 0; i caption');
if(chartCaption) {
var totalInterestFormatted = formatCurrency(data.interest.reduce((a, b) => a + b, 0));
var totalPrincipalFormatted = formatCurrency(data.principal.reduce((a, b) => a + b, 0));
chartCaption.textContent = `Visual representation of principal (${totalPrincipalFormatted}) vs. interest (${totalInterestFormatted}) paid in the first year.`;
}
}