Estimate your monthly mortgage payment and view the full amortization schedule.
Your monthly mortgage payment is calculated using the standard fixed-rate amortization formula, which spreads principal and interest across your loan term so that the loan is fully paid off by the final payment.
M = P · r / (1 − (1+r)^−n)
A mortgage payment is not one number, it is four stacked on top of each other: principal, interest, property tax and insurance. Lenders quote the whole stack as PITI, and it is the figure that actually leaves your account each month. This calculator works out the principal-and-interest portion exactly, then lets you layer the rest on top so the total is comparable to a real lender quote.
The core arithmetic is the amortising payment formula:
Interest is charged on the balance you still owe, so at the start of a 30-year term almost the entire payment is interest. On a £300,000 loan at 6% the first payment is roughly £1,500 of interest and £299 of principal. The split does not reach 50/50 until around year 18.
This is the single most useful thing to understand about a mortgage, and it has a practical consequence: overpayments made early are worth far more than the same amount paid late, because every pound of principal removed early avoids interest for the whole remaining term.
| Change | Effect on lifetime interest |
|---|---|
| Rate 1 percentage point lower | Very large — typically 12–15% less interest |
| Term 30 years to 25 years | Large — roughly 20% less interest, higher monthly |
| Deposit 10% to 20% | Large — smaller principal and usually removes PMI |
| One extra payment per year | Meaningful — often cuts 4–6 years off a 30-year term |
Rate matters more than almost anything else, which is why shopping the rate is worth more than shaving the price.
monthly into an escrow account.
often be removed once you cross that line — but usually only if you ask.
the same budget.
Start from what you can comfortably pay each month rather than the maximum a lender will approve. Work backwards to a price, then stress-test it: re-run the numbers two percentage points higher. If the payment at that rate would be uncomfortable, the loan is larger than it looks.
Then compare against the loan calculator for any other debt you carry, and use the amortization calculator to see the exact month your balance crosses a threshold that matters to you.
This calculator provides estimates for informational purposes only and does not constitute financial advice. Consult a mortgage professional for accurate loan terms.
No, this calculates principal and interest only. Add your local tax and insurance estimates separately for a full monthly cost picture.
Extra payments reduce your principal balance faster, shortening your loan term and reducing total interest paid. This calculator shows the standard schedule without extra payments.