Mortgage Repayment Calculator
Enter your mortgage amount, interest rate, and term to see your monthly repayment and the total cost of your mortgage.
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A capital repayment mortgage is repaid in equal monthly instalments. Each payment covers the interest accrued that month and a portion of the outstanding capital. Early in the term, most of each payment is interest; as the balance reduces over time, the interest portion shrinks and more of each payment goes towards capital. The calculator uses the standard mortgage amortisation formula to derive the monthly payment, then multiplies by the number of months to give the total amount repayable. Total interest is the difference between total repayable and the original loan amount.
The calculation assumes a fixed interest rate throughout the term. If you are on a tracker or variable rate, your actual payments will change if the rate moves.
Understanding your results
The monthly repayment is the amount you will pay each month to fully repay the mortgage by the end of the term at the rate entered. Total interest is the cost of borrowing — the higher the rate or the longer the term, the more interest you pay in total. Comparing different terms shows the trade-off: a longer term reduces monthly payments but increases total interest paid.
Frequently asked questions
What is the difference between a repayment and interest-only mortgage?
On a repayment mortgage, each monthly payment reduces the outstanding balance so the mortgage is fully repaid at the end of the term. On an interest-only mortgage, monthly payments cover only the interest, leaving the full original loan to be repaid at the end of the term via a separate repayment vehicle. Most residential mortgages in the UK are repayment mortgages.
Does this calculator work for fixed-rate and tracker mortgages?
The calculator works for both, but it assumes the rate you enter stays constant for the full term. For a fixed-rate mortgage this is accurate for the fixed period; for a tracker mortgage the actual payments will vary as the Bank of England base rate changes.
How does changing the term affect my repayments?
A longer term reduces the monthly payment but significantly increases the total interest paid over the life of the mortgage. A shorter term increases monthly payments but reduces total interest. The difference can be substantial — running the calculator with different terms illustrates this trade-off clearly.
Is this calculator suitable for buy-to-let mortgages?
Yes — the mathematics are identical for residential and buy-to-let capital repayment mortgages. Note that buy-to-let mortgages are also available on an interest-only basis, which this calculator does not cover.