Enter the amount you want to borrow, the interest rate and the term. You get the monthly payment, the total interest and what you will have repaid by the end, with a year-by-year schedule you can export month by month. Add your income to see your loan to income, the measure the Bank of England uses to limit high lending. The calculation is the same in England, Scotland, Wales and Northern Ireland.
Amount, rate and term
The amount is the mortgage itself: the price of the property less your deposit. Enter the yearly interest rate of the deal, not the APRC, which also counts fees. The term is in years, with extra months if you need them, up to 40 years.
Repayment or interest-only
With a repayment mortgage, each monthly payment covers that month’s interest and part of the loan, so you owe nothing at the end. With an interest-only mortgage you pay just the interest, which keeps payments lower, but the whole loan is still owed at the end of the term and you need a way to repay it.
When a fixed or tracker rate ends
The calculator applies one rate for the whole term. If your deal fixes or tracks a rate for a set period and then moves to another rate, run the calculation again for the rest of the term, with the follow-on rate and the balance owed at that point, which the yearly schedule shows.
Loan to income
Loan to income is the amount borrowed divided by your yearly income before tax, all applicants together. The Bank of England’s Financial Policy Committee limits lending at 4.5 times income or more to 15% of new mortgages across the UK, not counting further advances and retirement interest-only mortgages. Since 28 October 2026 that limit applies to the market as a whole rather than to each lender.
Rounding
The monthly payment is rounded to the nearest penny, with halves rounded up. Each month’s interest is worked out on the balance owed and rounded the same way, and the last payment is adjusted by a few pence so the balance ends at exactly zero. A lender that charges interest daily will show slightly different figures.
Monthly payment = P × r ÷ (1 − (1 + r)^−n), where P is the amount borrowed, r the yearly rate divided by 12 and n the number of monthly payments.
Each month: interest = balance owed × r; capital repaid = payment − interest.
Interest-only: monthly payment = P × r, and P is repaid with the last payment.
Loan to income = amount borrowed ÷ yearly income before tax.
Example: the Bank of England’s £130,000 over 25 years
The Bank of England’s explainer on interest rates takes a £130,000 mortgage paid off over 25 years: about £583 a month at 2.5% and £651 at 3.5%. The calculator gives £583.20 and £650.81. At 2.5% you repay £174,960.78 in all, of which £44,960.78 is interest; at 3.5% the interest rises to £65,243.22.
