UK Mortgage Calculator 2026
Work out the monthly payment, total repayment and total interest on a UK repayment (capital-and-interest) mortgage. Enter the amount you're borrowing, your interest rate and the term in years — the calculator uses the standard constant-payment annuity formula and works in pounds sterling. Free, instant, no signup.
Your mortgage repayment
- Monthly payment£1,461.48
- Total repayment (all payments)£438,442.53
- Total interest£188,442.53
- Number of payments300
How it's calculated
A UK repayment mortgage (capital-and-interest) is cleared by equal monthly instalments over the term. Each instalment covers the month's interest plus a slice of the capital, so the outstanding balance falls and the debt reaches zero with the final payment. Early on, most of each payment is interest because the balance is large; as the balance shrinks, more of every payment chips away at the capital. The instalment is sized with the standard annuity formula from three inputs: the amount borrowed, the term in years and the annual interest rate. The annual rate is converted to a monthly rate by dividing by 12 (and by 100 to turn a percentage into a decimal), and the term is converted to a number of monthly payments by multiplying the years by 12. If you enter 0%, the formula collapses to simply spreading the loan evenly across the months. The figure you enter is the initial (nominal) rate that sets your payment during a fixed or tracker deal — not the lender's APRC, which is a regulated all-in cost figure that is almost always higher because it folds in fees and the reversion to the Standard Variable Rate. This calculator assumes one constant rate for the whole term, which is realistic during an initial deal but a simplification once that deal ends. It models repayment mortgages only, not interest-only, and applies UK-wide (England, Wales, Scotland and Northern Ireland). It is general information, not financial advice.
M = P × i × (1 + i)^n / ((1 + i)^n − 1)
P = loan amount (capital borrowed)
i = monthly rate = annual rate ÷ 100 ÷ 12
n = number of payments = term in years × 12
If i = 0: M = P ÷ n
Total repayment = M (unrounded) × n
Total interest = Total repayment − PWorked example
Take a £250,000 loan at an initial rate of 5.0% over a 25-year term, with one constant rate and no product fees:
| Loan amount (P) | £250,000.00 |
| Number of payments (n)25 years × 12 | 300 |
| Monthly rate (i)5.0 ÷ 100 ÷ 12 = 0.0041666667 | 0.41667% |
| Growth factor (1 + i)^n1.0041666667^300 | 3.48129045 |
| Monthly payment (M)250000 × i × factor ÷ (factor − 1) | £1,461.48 |
| Total repaymentunrounded M × 300 | £438,442.53 |
| Total interest£438,442.53 − £250,000 | £188,442.53 |
So this borrower pays about £1,461.48 a month and, over the full 25 years, repays £438,442.53 in total — of which £188,442.53 is interest, roughly 75% on top of the amount borrowed. Note the total uses the unrounded monthly payment; multiplying the rounded £1,461.48 by 300 would introduce a small error.
When your result may differ
Your real-world payment can differ from this estimate in several ways. The biggest is the rate changing: this calculator assumes one constant rate for the whole term, but most UK borrowers take a 2- or 5-year fixed or tracker deal and then revert to the lender's Standard Variable Rate (SVR) — usually materially higher — unless they remortgage. Interest-only mortgages are not modelled here: those have lower monthly payments because you pay only interest, but the full capital is still owed at the end. Product and arrangement fees are excluded from the monthly figure, so compare deals on the regulated APRC, which blends fees and the reversion rate into one number and is almost always higher than the headline rate. Overpayments reduce the balance, shortening the term and cutting total interest, subject to any early repayment charge. Finally, lenders round and apply interest on slightly different day-count conventions, so a real statement may vary by a few pounds.
Rates and thresholds
How each input moves the £250,000 / 25-year payment. Initial rate held constant; payments rounded to the nearest pound.
| Initial rate | Monthly payment | Total repayment | Total interest |
|---|---|---|---|
| 3.0% | £1,186 | £355,658 | £105,658 |
| 4.0% | £1,320 | £395,878 | £145,878 |
| 5.0% | £1,461 | £438,443 | £188,443 |
| 6.0% | £1,611 | £483,226 | £233,226 |
| 7.0% | £1,767 | £530,084 | £280,084 |
Sources & legal basis
| Source | What it covers | Last checked |
|---|---|---|
| MoneyHelper — Interest-only and repayment mortgages explained | How repayment (capital-and-interest) mortgages are repaid and how they differ from interest-only | |
| FCA Handbook — MCOB 10A.1 Calculation of the APRC | The regulated method for the Annual Percentage Rate of Charge lenders must display | |
| FCA — Annual Percentage Rate of Charge (APRC) calculations | Why APRC assumes the rate continues and so usually exceeds the headline rate | |
| MoneyHelper — Mortgage calculators | General guidance on UK mortgage costs and affordability |
Update log
- — Refreshed worked example for a £250,000 loan at 5.0% over 25 years.
- — Added structured worked example, a rate-sensitivity table and a source table; expanded the explanation of the annuity formula and the APRC distinction.
Frequently asked questions
How is a UK mortgage monthly payment calculated?
A repayment mortgage uses the annuity formula M = P × i × (1+i)^n / ((1+i)^n − 1), where P is the amount borrowed, i is the monthly interest rate (the annual rate divided by 12 and by 100) and n is the number of monthly payments (years × 12). The payment stays the same every month, but at the start most of it is interest and only a small part is capital — the proportion flips over time. For example, £250,000 at 5.0% over 25 years gives 300 payments and a monthly payment of £1,461.48. If the rate is 0% the payment is simply the loan divided by the number of months.
What's the difference between a repayment and an interest-only mortgage?
On a repayment (capital-and-interest) mortgage each monthly payment covers the interest plus a slice of the capital, so the loan is fully paid off by the end of the term — that's what this calculator models. On an interest-only mortgage you pay only the interest each month, your payments are lower, but the entire amount borrowed is still owed at the end and must be repaid some other way (for example from savings or by selling the property). Most UK residential mortgages today are repayment.
What is APRC and why is it higher than my interest rate?
APRC (Annual Percentage Rate of Charge) is the standardised headline cost figure UK lenders must display under FCA rules implementing the Mortgage Credit Directive. It blends your initial rate, the lender's reverted rate (usually the Standard Variable Rate) for the rest of the term, and fees such as arrangement, product and valuation charges into one annualised percentage — so it's almost always higher than the initial rate. The rate you type into this calculator is the initial/nominal rate that sizes your payment; use the APRC to compare deals, not the headline rate.
What is total repayment and total interest?
Total repayment is everything you'll pay over the whole term — the unrounded monthly payment multiplied by the number of payments. Total interest is that figure minus the amount you borrowed: it's the cost of the loan on top of the capital. In the worked example (£250,000 at 5.0% over 25 years), the total repayment over 300 payments is £438,442.53 and the total interest is £188,442.53. Note we multiply the unrounded monthly payment by 300; rounding the monthly figure first would introduce a small error.
What happens when my fixed or tracker deal ends?
This calculator assumes a single constant rate for the whole term, which is realistic during an initial deal — typically a 2- or 5-year fixed rate (payment locked) or a tracker that follows the Bank of England base rate plus a margin. When that deal ends, the mortgage usually reverts to the lender's Standard Variable Rate (SVR), which the lender sets and is typically materially higher. At that point your real-world monthly payment can change, so most borrowers remortgage onto a new deal before the reversion.
Can I reduce the total interest I pay?
Yes. A larger deposit (a smaller loan amount), a lower interest rate, or a shorter term all cut the total interest — though a shorter term raises the monthly payment. Overpayments are powerful too: paying extra reduces the outstanding balance, which shortens the term and lowers total interest, subject to any early repayment charge limits in your deal. Remember that product and arrangement fees aren't part of the monthly payment shown here, and this is general information, not financial advice.