Calculate your mortgage payments by paying every two weeks, plus the impact of extra payments.
Payment Summary
Regular Bi-Weekly Payment:$0.00
Total Number of Payments:0
Total Paid Over Life of Loan:$0.00
Total Interest Paid:$0.00
Loan Paid Off In:0 Years
Total Savings from Extra Payments:$0.00
Understanding Bi-Weekly Mortgage Payments and Extra Payments
A bi-weekly mortgage payment plan is a strategy where you make a payment every two weeks instead of the traditional monthly payment. Since there are 52 weeks in a year, this results in 26 half-payments annually. This is equivalent to 13 full monthly payments (26 / 2 = 13), whereas a standard monthly plan involves only 12 payments. This extra payment per year goes directly towards your principal balance, helping you pay off your mortgage faster and save on interest.
How Bi-Weekly Payments Work
In a true bi-weekly plan (often set up through your lender), half of your normal monthly mortgage payment is automatically deducted from your bank account every two weeks. Over the course of a year, these 26 half-payments equal one extra full monthly payment. This accelerates principal reduction because each half-payment is applied to the loan immediately, rather than accumulating and being applied as a lump sum at the end of the month.
Benefits of Bi-Weekly Payments
Faster Payoff: By making one extra monthly payment annually, you can shave years off your mortgage term.
Significant Interest Savings: Paying down the principal faster means less interest accrues over the life of the loan.
Builds Equity Quicker: More of your payment goes towards owning your home.
Adding Extra Payments
The calculator above goes a step further by allowing you to specify an *additional* fixed amount you'd like to pay every two weeks, on top of the standard bi-weekly payment amount. This could be a bonus, tax refund, or simply a commitment to pay more. By consistently adding extra funds, you amplify the benefits of the bi-weekly strategy, leading to even faster payoff times and greater interest savings.
The Math Behind the Calculator
The calculation involves several steps:
Calculate the Standard Monthly Payment (P&I): We use the standard mortgage payment formula:
M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1]
Where:
M = Monthly Payment
P = Principal Loan Amount
i = Monthly Interest Rate (Annual Rate / 12)
n = Total Number of Payments (Loan Term in Years * 12)
Determine the Bi-Weekly Payment: The standard bi-weekly payment is half of the calculated monthly payment.
Bi-Weekly Payment = M / 2
Calculate Total Bi-Weekly Payment with Extra:Total Bi-Weekly Payment = (M / 2) + Extra Bi-Weekly Payment
Simulate Amortization with Bi-Weekly Payments: This is the core of the calculation. We simulate the loan's amortization period by period, applying the Total Bi-Weekly Payment. Since payments are made every two weeks, we need to adjust the interest calculation. The effective interest rate per period is the annual rate divided by 26 (the number of bi-weekly periods in a year).
Effective Bi-Weekly Interest Rate = Annual Interest Rate / 26
We iterate through each payment, reducing the principal and calculating the interest due for that period. The loan is paid off when the principal reaches zero.
Calculate Total Interest Paid: Sum of all interest paid throughout the loan term.
Calculate Total Paid: Sum of all principal and interest payments made.
Calculate Loan Paid Off In: Determine the total time in years it took to pay off the loan using the bi-weekly schedule with extra payments.
Calculate Total Savings: Compare the total interest paid with the extra payments versus the total interest that *would have been paid* on a standard monthly payment schedule over the original loan term.
Savings = (Total Interest on Standard Monthly Payments) - (Total Interest Paid with Bi-Weekly + Extra)
Note: For simplicity in this calculator, we calculate total interest paid based on the *actual* payoff time of the bi-weekly plan and compare it to the total interest that would have been paid on a standard monthly plan over the *original* loan term.
When to Use This Calculator
When considering a mortgage and wanting to understand the benefits of accelerating payments.
If you have a current mortgage and want to see how making extra payments every two weeks could save you money and time.
To compare the financial impact of different extra payment amounts.
Disclaimer: This calculator provides an estimate for educational purposes. Actual results may vary based on lender policies, exact payment application dates, and potential changes in interest rates (if you have an adjustable-rate mortgage).
function calculateBiWeeklyMortgage() {
var loanAmount = parseFloat(document.getElementById("loanAmount").value);
var annualInterestRate = parseFloat(document.getElementById("annualInterestRate").value);
var loanTermYears = parseInt(document.getElementById("loanTermYears").value);
var extraPaymentAmount = parseFloat(document.getElementById("extraPaymentAmount").value);
// Input validation
if (isNaN(loanAmount) || loanAmount <= 0) {
alert("Please enter a valid Loan Amount.");
return;
}
if (isNaN(annualInterestRate) || annualInterestRate <= 0) {
alert("Please enter a valid Annual Interest Rate.");
return;
}
if (isNaN(loanTermYears) || loanTermYears <= 0) {
alert("Please enter a valid Loan Term in Years.");
return;
}
if (isNaN(extraPaymentAmount) || extraPaymentAmount 0) {
standardMonthlyPayment = loanAmount * (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfMonthlyPayments)) / (Math.pow(1 + monthlyInterestRate, numberOfMonthlyPayments) – 1);
} else {
standardMonthlyPayment = loanAmount / numberOfMonthlyPayments; // Handle 0 interest rate
}
// Calculate regular bi-weekly payment (half of standard monthly)
var regularBiWeeklyPayment = standardMonthlyPayment / 2;
document.getElementById("regularBiWeeklyPayment").innerText = "$" + regularBiWeeklyPayment.toFixed(2);
// Total bi-weekly payment including extra
var totalBiWeeklyPayment = regularBiWeeklyPayment + extraPaymentAmount;
// Amortization simulation for bi-weekly payments with extra
var remainingBalance = loanAmount;
var totalPaid = 0;
var totalInterestPaid = 0;
var paymentCount = 0;
var effectiveBiWeeklyInterestRate = annualInterestRate / 100 / 26; // Rate per bi-weekly period
while (remainingBalance > 0) {
var interestForPeriod = remainingBalance * effectiveBiWeeklyInterestRate;
var principalForPeriod = totalBiWeeklyPayment – interestForPeriod;
// Ensure we don't overpay the last payment
if (principalForPeriod > remainingBalance) {
principalForPeriod = remainingBalance;
totalBiWeeklyPayment = interestForPeriod + principalForPeriod; // Adjust last payment amount
}
remainingBalance -= principalForPeriod;
totalInterestPaid += interestForPeriod;
totalPaid += totalBiWeeklyPayment;
paymentCount++;
// Safety break for potential infinite loops (e.g., very high interest rates or incorrect inputs)
if (paymentCount > loanTermYears * 26 * 5) { // Arbitrary limit to prevent very long loops
alert("Calculation exceeded maximum iterations. Please check your inputs.");
return;
}
}
var totalPaidOffYears = (paymentCount / 26);
var loanPaidOffInYearsText = totalPaidOffYears.toFixed(2) + " Years";
// Calculate total interest if paid monthly over original term for comparison
var totalInterestStandardMonthly = (standardMonthlyPayment * numberOfMonthlyPayments) – loanAmount;
// Calculate savings
var totalSavings = totalInterestStandardMonthly – totalInterestPaid;
if (totalSavings < 0) totalSavings = 0; // Savings can't be negative
document.getElementById("totalPayments").innerText = paymentCount;
document.getElementById("totalPaid").innerText = "$" + totalPaid.toFixed(2);
document.getElementById("totalInterestPaid").innerText = "$" + totalInterestPaid.toFixed(2);
document.getElementById("loanPaidOffInYears").innerText = loanPaidOffInYearsText;
document.getElementById("totalSavings").innerText = "$" + totalSavings.toFixed(2);
}