Skip to content
Buying Budget

Mortgage Repayment Calculator

Estimate only

Enter a mortgage amount, an interest rate assumption and a term to see an illustrative monthly payment, the total you would repay and how much of that is interest. The rate you enter is an assumption — real payments depend on the product you are accepted for.

Repayment type

Estimated monthly payment

£1,169.18

Over 25 years at 5%, capital and interest.

Total repaid

£350,754

Total interest

£150,754

Capital repaid by end of term

£200,000

Estimate only

This illustration assumes the same interest rate for the whole term. In practice most UK mortgages have a fixed or discounted period and then move to the lender's variable rate, so your payment is likely to change.

How this calculation works

Repayment mortgages use the standard annuity formula, applied monthly. Interest-only payments are simply the monthly interest on the balance, with the capital outstanding throughout. The amortisation table applies the payment month by month and groups the result into years.

M = P · r ÷ (1 − (1 + r)^−n)
P = mortgage amount, r = annual rate ÷ 12, n = term in months
Interest-only: M = P · annual rate ÷ 12

Assumptions

  • One constant interest rate for the whole term.
  • Interest is calculated monthly on the outstanding balance.
  • No product fees, insurance or overpayments are included.

Limitations

  • Lenders calculate interest daily, monthly or annually; small differences in the monthly figure are normal.
  • Fixed-rate periods, rate changes and payment holidays are not modelled.
  • This is an illustration, not a quotation or an offer.

Last reviewed: 1 September 2026 · Calculation version 1.0.0

Next in your journey

First-Time Buyer Costs Calculator

Add up deposit, property tax, legal fees, survey, mortgage fees and moving costs — every assumption editable.

Open Buying costs calculator

All calculators