Does this include fees or insurance?

No — it's the pure loan calculation. Your actual monthly cost will also include buildings insurance, arrangement fees, and possibly life insurance.

How is the monthly payment calculated?

Standard amortization: M = P × r(1+r)^n / ((1+r)^n − 1), where P is principal, r is the monthly interest rate, and n is the number of months.

Are overpayments always worth it?

If your mortgage rate is higher than what you'd earn on savings (after tax), yes. Check your lender's overpayment allowance first — most permit 10% per year without penalty.

What if my rate changes during the term?

This assumes a fixed rate for the full term. In practice, most UK mortgages re-fix every 2–5 years. Re-run this calculator when you remortgage.

Mortgage Repayment Calculator

Work out your monthly mortgage payment, total interest paid, and how much you save by overpaying.

Your details

Loan amount

Interest rate

Term (years)

Repayment type

Monthly overpayment (optional)

Monthly payment

£1,498

Total interest

£199,436

Total repaid

£449,436

Remaining balance over time

How this is calculated

A repayment mortgage splits each monthly payment between interest on the outstanding balance and a chunk of the principal. Early on, most of the payment is interest; over time the balance falls and more of each payment reduces the principal.

An interest-only mortgage keeps the balance constant — you only pay interest each month, and repay the full principal at the end. Monthly payments are lower, but total interest paid is much higher.

Overpayments go straight against the principal, which reduces the interest charged on every subsequent month. Even a small monthly overpayment can shave years and thousands in interest off the total.