Mortgage Repayment Calculator
Work out exactly what your monthly mortgage payment will be — and how much interest you'll pay over the full term.
Monthly payment
£1,111.66
- Total repaid
- £333,499.49
- Total interest
- £133,499.49
- Interest as % of loan
- 66.75%
Monthly payments assume a capital repayment mortgage with monthly compounding. The actual rate from your lender will depend on your LTV, credit score, and deal type. Always check the APRC (Annual Percentage Rate of Charge) for a true like-for-like comparison.
How to use this calculator
Enter the loan amount (the amount you are borrowing, not the property price), the annual interest rate your lender has quoted, and the mortgage term in years. The calculator returns the monthly payment, total amount repaid, and total interest charged.
How the calculation works
Uses the standard amortisation formula: P = L × r / (1 − (1+r)^−n), where L is the loan amount, r is the monthly interest rate (annual rate ÷ 12), and n is the total number of monthly payments. Each payment covers the accrued interest for that month plus a portion of the outstanding principal.
Worked example
A £200,000 mortgage at 4.5% over 25 years: monthly rate = 4.5% ÷ 12 = 0.375%. Monthly payment = £200,000 × 0.00375 / (1 − 1.00375^−300) ≈ £1,111. Total repaid ≈ £333,300. Total interest ≈ £133,300.
Frequently asked questions
What is the difference between the interest rate and the APRC?
The interest rate is the rate applied to your outstanding balance each year. The APRC (Annual Percentage Rate of Charge) includes the interest rate plus any mandatory fees — arrangement fee, booking fee, valuation — expressed as a single annual percentage. The APRC is the legally required comparison figure and gives a more accurate picture of the true annual cost than the headline rate alone.
How does a fixed rate differ from a tracker or SVR mortgage?
A fixed-rate mortgage locks the interest rate for a set period (typically 2, 3, or 5 years), so your monthly payment stays the same regardless of what happens to the Bank of England base rate. A tracker mortgage moves in line with the base rate plus a set margin — payments can go up or down each time the base rate changes. An SVR (Standard Variable Rate) is the lender's own rate, usually higher than fixes and trackers, and changes at the lender's discretion.
Can I overpay my mortgage?
Most fixed-rate deals allow overpayments of up to 10% of the outstanding balance per year without an early repayment charge (ERC). Overpaying reduces your outstanding balance, which reduces the interest charged each month and shortens the term. Even small regular overpayments can save thousands in interest over a 25-year mortgage.
Does the calculator include fees?
No — the calculator shows the repayment based purely on loan amount, rate, and term. Arrangement fees, valuation fees, solicitor costs, and broker fees are excluded. Add those costs to your planning separately. For buy-to-let mortgages, use the BTL mortgage calculator which shows gross yield and ICR alongside the payment.
What happens to my payment if the interest rate changes?
If you are on a tracker or SVR, your monthly payment changes each time the rate changes. Re-run the calculator with the new rate to see the updated payment. If you are mid-fix, your rate is locked until the fixed period ends — at which point you will remortgage or roll onto the SVR.
How much deposit do I need?
Most lenders offer mortgages from 5% deposit (95% LTV), but the lowest rates are available at 60–75% LTV. A 10% deposit (90% LTV) unlocks significantly better rates than 5%. First-time buyers may qualify for the Mortgage Guarantee Scheme, which supports 95% LTV lending from participating lenders.