How are monthly mortgage repayments calculated?

For a repayment mortgage, the monthly payment is calculated using the standard amortisation formula from your mortgage amount, interest rate and term, so the balance clears by the end of the term. For an interest-only mortgage, the monthly cost is just the interest on the balance and the amount borrowed is still owed at the end. This calculator assumes the rate stays the same for the whole term; in reality most UK mortgages re-fix every few years and the rate then changes. Figures are illustrative — your real payment depends on the rate and product you qualify for.

What is the difference between a repayment and an interest-only mortgage?

A repayment mortgage pays off both the interest and the capital each month, so the mortgage is cleared by the end of the term. An interest-only mortgage pays only the interest, so the monthly cost is lower but the full amount borrowed remains owed at the end and needs a separate repayment plan. A regulated mortgage adviser can explain which is suitable for your circumstances.

Mortgage Repayment Calculator

See what a mortgage could cost you each month, and the total you would pay back over the full term once interest and fees are added in. Figures are illustrative and not a quote or mortgage offer.

For illustration purposes only

The figures this calculator produces are illustrative and based only on the information you enter. They are a guide — not a quote, a mortgage offer, or financial advice. What you can actually borrow, and the rate you pay, depend on the lender’s assessment of your full circumstances.

Speak to a qualified professionalFor a recommendation tailored to you, speak to an FCA-regulated mortgage adviser — we search the whole of market. Checking your options is free and does not affect your credit score.

No obligationThis is an estimate only. The binding figures — your real monthly payment, total cost and any reversion rate — come with your mortgage offer and its illustration (ESIS).

Niche Advice Limited accepts no responsibility for any decisions made on the basis of this calculator. Niche Advice Limited is authorised and regulated by the Financial Conduct Authority (FCA Reference: 750263). Niche Advice Limited is a credit broker, not a lender. Your home may be repossessed if you do not keep up repayments on a mortgage secured against it.

Lender criteria and interest rates change frequently. Always confirm any figure with a qualified, FCA-regulated mortgage adviser before acting on it.

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This is a guide only. For figures tailored to you — with no upfront fees — request a callback from an FCA-regulated adviser.

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