#mortgage-refi-calculator-wrapper {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
max-width: 800px;
margin: 0 auto;
padding: 20px;
background: #fff;
color: #333;
}
.refi-calc-container {
background-color: #f8f9fa;
border: 1px solid #e9ecef;
border-radius: 8px;
padding: 30px;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
margin-bottom: 40px;
}
.refi-row {
display: flex;
flex-wrap: wrap;
margin: 0 -10px;
}
.refi-col {
flex: 1;
min-width: 250px;
padding: 0 10px;
margin-bottom: 20px;
}
.refi-label {
display: block;
font-weight: 600;
margin-bottom: 8px;
font-size: 14px;
color: #495057;
}
.refi-input {
width: 100%;
padding: 12px;
border: 1px solid #ced4da;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
transition: border-color 0.2s;
}
.refi-input:focus {
border-color: #007bff;
outline: none;
}
.refi-btn {
background-color: #007bff;
color: white;
border: none;
padding: 15px 30px;
font-size: 18px;
font-weight: 700;
border-radius: 4px;
cursor: pointer;
width: 100%;
transition: background-color 0.2s;
margin-top: 10px;
}
.refi-btn:hover {
background-color: #0056b3;
}
.refi-results {
margin-top: 30px;
border-top: 2px solid #e9ecef;
padding-top: 20px;
display: none;
}
.result-grid {
display: grid;
grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
gap: 20px;
}
.result-card {
background: white;
padding: 20px;
border-radius: 6px;
border: 1px solid #dee2e6;
text-align: center;
}
.result-title {
font-size: 13px;
text-transform: uppercase;
letter-spacing: 1px;
color: #6c757d;
margin-bottom: 10px;
}
.result-value {
font-size: 24px;
font-weight: 800;
color: #212529;
}
.result-value.positive {
color: #28a745;
}
.result-value.negative {
color: #dc3545;
}
.refi-content {
line-height: 1.6;
font-size: 16px;
color: #444;
}
.refi-content h2 {
margin-top: 30px;
font-size: 24px;
color: #222;
}
.refi-content h3 {
margin-top: 25px;
font-size: 20px;
color: #333;
}
.refi-content p {
margin-bottom: 15px;
}
.refi-content ul {
margin-bottom: 15px;
padding-left: 20px;
}
.refi-content li {
margin-bottom: 8px;
}
function calculateRefinance() {
// Get inputs
var currentBalance = parseFloat(document.getElementById('currentBalance').value);
var currentRate = parseFloat(document.getElementById('currentRate').value);
var remainingYears = parseFloat(document.getElementById('remainingYears').value);
var refiCosts = parseFloat(document.getElementById('refiCosts').value);
var newRate = parseFloat(document.getElementById('newRate').value);
var newTerm = parseFloat(document.getElementById('newTerm').value);
// Validation
if (isNaN(currentBalance) || isNaN(currentRate) || isNaN(remainingYears) ||
isNaN(refiCosts) || isNaN(newRate) || isNaN(newTerm)) {
alert("Please enter valid numbers in all fields.");
return;
}
// 1. Calculate Old Monthly Payment (projected for remaining term)
// Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
var monthlyRateOld = (currentRate / 100) / 12;
var numPaymentsOld = remainingYears * 12;
var oldPayment = 0;
if (monthlyRateOld === 0) {
oldPayment = currentBalance / numPaymentsOld;
} else {
oldPayment = currentBalance * (monthlyRateOld * Math.pow(1 + monthlyRateOld, numPaymentsOld)) / (Math.pow(1 + monthlyRateOld, numPaymentsOld) – 1);
}
// 2. Calculate New Monthly Payment
// Note: We assume closing costs are paid out of pocket for this calculation to determine Break-Even clearly,
// rather than rolled into the loan which complicates the LTV logic.
var monthlyRateNew = (newRate / 100) / 12;
var numPaymentsNew = newTerm * 12;
var newPayment = 0;
if (monthlyRateNew === 0) {
newPayment = currentBalance / numPaymentsNew;
} else {
newPayment = currentBalance * (monthlyRateNew * Math.pow(1 + monthlyRateNew, numPaymentsNew)) / (Math.pow(1 + monthlyRateNew, numPaymentsNew) – 1);
}
// 3. Calculate Metrics
var monthlyDiff = oldPayment – newPayment;
var totalCostOld = oldPayment * numPaymentsOld;
var totalCostNew = (newPayment * numPaymentsNew) + refiCosts;
var lifetimeNet = totalCostOld – totalCostNew;
var breakEvenMonths = 0;
var breakEvenText = "";
if (monthlyDiff > 0) {
breakEvenMonths = refiCosts / monthlyDiff;
var years = Math.floor(breakEvenMonths / 12);
var months = Math.ceil(breakEvenMonths % 12);
if (years > 0) {
breakEvenText = years + " yr " + months + " mo";
} else {
breakEvenText = months + " months";
}
} else {
breakEvenText = "N/A (Cost Increase)";
}
// 4. Display Results
var monthlySavingsEl = document.getElementById('monthlySavings');
var lifetimeSavingsEl = document.getElementById('lifetimeSavings');
var breakEvenEl = document.getElementById('breakEven');
// Format Currency
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 0,
maximumFractionDigits: 0,
});
monthlySavingsEl.innerText = formatter.format(monthlyDiff);
lifetimeSavingsEl.innerText = formatter.format(lifetimeNet);
breakEvenEl.innerText = breakEvenText;
// Styling for positive/negative results
monthlySavingsEl.className = 'result-value ' + (monthlyDiff >= 0 ? 'positive' : 'negative');
lifetimeSavingsEl.className = 'result-value ' + (lifetimeNet >= 0 ? 'positive' : 'negative');
// Show results
document.getElementById('resultsArea').style.display = 'block';
}
Refinance Savings Calculator
Monthly Savings
Lifetime Net Savings
Break-Even Period
* Comparison excludes taxes and insurance. Negative values indicate a loss.
About This Mortgage Refinance Calculator
Deciding whether to refinance your mortgage is a significant financial decision. This calculator helps you determine if refinancing makes sense by analyzing your potential monthly savings, lifetime interest reduction, and the "break-even" point where your savings outweigh the closing costs.
How to Use the Calculator
To get the most accurate results, you will need the following information:
- Current Principal Balance: The amount currently left on your mortgage. Check your latest loan statement for the exact figure.
- Current Interest Rate & Remaining Term: Enter your existing rate and how many years you have left to pay. This helps calculate what you would pay if you don't refinance.
- Refinance Closing Costs: Refinancing isn't free. Enter the estimated closing costs (appraisal fees, title insurance, origination fees). This is crucial for calculating your break-even point.
- New Loan Details: Enter the interest rate and term (length) of the new loan you are considering.
Understanding the Results
Monthly Savings: This is the difference between your current principal and interest payment and the new proposed payment. A positive number means more cash flow in your pocket every month.
Lifetime Net Savings: This looks at the "big picture." It compares the total amount you would pay over the remaining life of your current loan versus the total amount you will pay over the life of the new loan (including closing costs). Sometimes a lower monthly payment results in a higher lifetime cost if you extend the loan term significantly.
Break-Even Period: This is arguably the most important metric. It tells you how long it takes for your monthly savings to pay back the upfront closing costs. If you plan to move or sell the house before this period ends, refinancing may not be financially sound.
When Should You Refinance?
Generally, refinancing is a good idea if:
- You can lower your interest rate by at least 0.50% to 1.00%.
- You plan to stay in the home longer than the break-even period.
- You want to switch from an adjustable-rate mortgage (ARM) to a fixed-rate mortgage for stability.
- You want to shorten your loan term (e.g., 30-year to 15-year) to build equity faster and save on total interest.