UK Mortgage Calculator
Work out your monthly payment, total interest, and see how your mortgage debt falls over time. Switch between repayment and interest-only. When you want a strategy — not just numbers — hand off to the AI agent.
Basic mortgage calculator
Enter your loan details. Results update instantly.
Total cost over the full 25-year term.
- Principal£250,000What you actually borrowed — returned to the lender.60%
- Interest£166,874The price of borrowing. Pure cost.40%
Year-by-year balance, assuming the rate stays at 4.5%.
Cumulative — early years are interest-heavy, later years skew to capital.
Year-by-year amortisation
| Year | Monthly | Interest (yr) | Capital (yr) | Balance end-yr |
|---|---|---|---|---|
| 1 | £1,390 | £11,137 | £5,538 | £244,462 |
| 2 | £1,390 | £10,882 | £5,793 | £238,669 |
| 3 | £1,390 | £10,616 | £6,059 | £232,610 |
| 4 | £1,390 | £10,338 | £6,337 | £226,273 |
| 5 | £1,390 | £10,047 | £6,628 | £219,645 |
| 6 | £1,390 | £9,742 | £6,933 | £212,712 |
| 7 | £1,390 | £9,424 | £7,251 | £205,461 |
| 8 | £1,390 | £9,091 | £7,584 | £197,876 |
| 9 | £1,390 | £8,742 | £7,933 | £189,943 |
| 10 | £1,390 | £8,378 | £8,297 | £181,646 |
| 11 | £1,390 | £7,997 | £8,678 | £172,968 |
| 12 | £1,390 | £7,598 | £9,077 | £163,891 |
| 13 | £1,390 | £7,181 | £9,494 | £154,397 |
| 14 | £1,390 | £6,745 | £9,930 | £144,466 |
| 15 | £1,390 | £6,288 | £10,386 | £134,080 |
| 16 | £1,390 | £5,811 | £10,864 | £123,216 |
| 17 | £1,390 | £5,312 | £11,363 | £111,853 |
| 18 | £1,390 | £4,790 | £11,885 | £99,969 |
| 19 | £1,390 | £4,244 | £12,431 | £87,538 |
| 20 | £1,390 | £3,673 | £13,002 | £74,536 |
| 21 | £1,390 | £3,076 | £13,599 | £60,937 |
| 22 | £1,390 | £2,451 | £14,224 | £46,713 |
| 23 | £1,390 | £1,798 | £14,877 | £31,836 |
| 24 | £1,390 | £1,114 | £15,561 | £16,276 |
| 25 | £1,390 | £399 | £16,276 | £0 |
Could you save thousands by switching?
LadderIQ's AI agent takes your numbers, the live UK market, and your deal end date — and tells you whether to switch, overpay, or sit tight. Free, no sign-up to try.
How this calculator works
For a repayment mortgage we use the standard UK amortisation formula: each month you pay interest on the remaining balance plus a slice of principal, sized so the loan clears at the end of the term. Early years are interest-heavy; principal pays down faster as the balance shrinks. The chart shows your remaining debt year by year.
For an interest-only mortgage you pay only the interest each month — the balance stays flat and the full principal is due at the end of the term, usually paid off via savings, sale, or a remortgage. Cheaper monthly, far more expensive total.
Fees can be paid upfront or added to the loan. Adding them to the loan increases your monthly payment and total interest, but preserves cash on day one.
Estimates only — not regulated financial advice. Rates and product fees change daily; figures are based on the inputs you provide.