Mortgage Calculator
Calculate your monthly repayment, total interest and full amortisation schedule.
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$
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Monthly payment
$0
principal + interest
Loan amount
$0
Total cost
$0
Total interest
$0
Interest %
0%
How is a mortgage payment calculated?
Monthly mortgage payments are calculated using the standard amortisation formula. Each payment covers the interest accrued that month plus a portion of the principal. In the early years, most of each payment goes to interest; over time, more goes to principal. This is why the total interest over a 30-year mortgage can equal or exceed the original loan amount.
The formula is: M = P × [r(1+r)ⁿ] / [(1+r)ⁿ−1], where P is the loan principal, r is the monthly interest rate, and n is the total number of payments. This calculator does not include property tax, home insurance, or PMI — your actual monthly outgoing will be higher.
How to Use
- Enter the home price and down payment (or drag the percentage slider).
- Enter your annual interest rate.
- Select the loan term (10, 15, 20 or 30 years).
- Your monthly payment and total cost update instantly.
- Click Show amortisation schedule to see a full year-by-year breakdown.
Frequently Asked Questions
Significantly. On a $400,000 30-year mortgage, the difference between a 5% and 7% rate is approximately $530/month — and over $190,000 in total interest. Each 0.5% increase adds roughly $130–200/month depending on loan size. This is why even small rate differences are worth shopping around for.
A 15-year mortgage typically has a lower interest rate and saves a very large amount in total interest — often hundreds of thousands of dollars. However, the monthly payment is substantially higher (roughly 40–50% more). A 30-year loan gives more month-to-month flexibility. Many financial advisors suggest the 30-year if the payment difference is invested, since investment returns can outpace mortgage interest savings.
No. All calculations happen entirely in your browser. Nothing is sent to any server.