Mortgage calculator
Monthly payment, total interest, and a year-by-year breakdown of where the money goes.
- Runs in your browser — nothing you enter is uploaded
- No sign-up, no quotas, free to use as often as you like
How it works
The number everyone is shown is the monthly payment, because it is the smallest and most comforting figure involved. The numbers that decide whether the mortgage is a good idea are the total interest and how slowly the balance moves in the early years. This shows all three.
The amortisation schedule
Underneath the summary is a year-by-year table: interest paid, principal paid, and the balance still owed. It is worth reading once, because it is genuinely surprising. On a typical 25-year mortgage the first year's payments are mostly interest, and it takes well over a decade before principal overtakes it. That is not a trick — it is simply what happens when interest is charged on a balance that has barely moved yet.
Tax and insurance
Lenders quote principal and interest, then add property tax and insurance separately, which is why the figure you were told rarely matches the figure that leaves your account. Enter the yearly amounts and the total monthly cost is shown alongside the loan payment.
The deposit matters twice
A larger deposit reduces the amount borrowed, and it usually unlocks a better rate as well. The calculator shows your deposit as a percentage of the price, because that percentage is the number lenders price against — the thresholds at 10%, 20% and 25% are where rates tend to step.
What this does not include
Arrangement and valuation fees, mortgage insurance where a small deposit requires it, early-repayment charges, service charges, and any rate that changes partway through. A real quote includes those, which is why an official APR is normally higher than the plain rate typed in here. Treat this as a comparison tool, not an offer.
Currency
None is assumed. The figures are just numbers, so the result is the same whichever currency you are borrowing in.
Mortgage calculator — questions
Is this a repayment or interest-only mortgage?
Repayment. Each payment covers that month's interest and reduces the balance with the rest, which is the standard structure.
Does it include fees?
No. Arrangement fees, insurance and early-repayment charges are excluded, which is why a lender's APR is usually higher than the rate you enter.
Why is so much of my early payment interest?
Because interest is charged on the outstanding balance, which is at its largest at the start. The schedule shows exactly how the balance shifts.
Can I model overpayments?
Not directly. A rough way to see the effect is to shorten the term — the monthly payment rises and the total interest falls sharply, which is what overpaying achieves.
Does anything get sent anywhere?
No. It is arithmetic in your browser. Nothing you type is transmitted, stored or logged.