At the Bank of England's latest quoted mortgage rate, every £100,000 of repayment mortgage costs about £546 a month over a 25-year term. Double the loan and you double the payment; halve it and you halve it. Because a repayment mortgage's monthly cost moves in a straight line with the amount borrowed, one number does most of the work — and you can rebuild the cost of almost any mortgage from it.
The rate that anchors everything below is the 75% loan-to-value five-year fixed rate of 4.32%, the most recent point in the Bank of England's quoted household interest rates series (April 2026, figures fetched 5 August 2026). At that rate, £100,000 repaid over 25 years costs £545.67 a month.
The one-number method
A repayment mortgage is level-payment: you pay the same amount every month, and the split between interest and capital shifts gradually over the term. For a fixed rate and term, the monthly payment is simply the loan size multiplied by a constant. At 4.32% over 25 years that constant works out at about £5.46 per £1,000 borrowed, or £545.67 per £100,000.
That gives a quick rule for any loan:
Monthly payment ≈ (loan ÷ £100,000) × £545.67
So a £150,000 loan costs about £819 a month, a £250,000 loan about £1,364, and a £400,000 loan about £2,183 — all at the current quoted rate over 25 years.
Cost per £100,000, by term and rate
Two things move the monthly figure: the rate and the term. The table shows the monthly cost of each £100,000 borrowed at the current quoted rate, and at one percentage point either side of it. The 3.32% and 5.32% rows are an illustration of rate sensitivity, not a forecast.
| Rate | 20 years | 25 years | 30 years | 35 years |
|---|---|---|---|---|
| 3.32% | £570.75 | £491.02 | £439.06 | £402.93 |
| 4.32% (current) | £622.97 | £545.67 | £496.05 | £462.17 |
| 5.32% | £677.76 | £603.38 | £556.55 | £525.28 |
Reading across the current-rate row: stretching a £100,000 loan from 20 to 35 years cuts the monthly payment from about £623 to £462 — roughly £161 less a month. Reading down a column: a one-percentage-point change in the rate moves the 25-year figure by about £55 a month for every £100,000 borrowed.
The longer-term trade-off
A longer term lowers the monthly payment but raises the total interest paid, because the debt is outstanding for more years. At 4.32%, per £100,000 borrowed:
| Term | Monthly payment | Total repaid | Interest paid |
|---|---|---|---|
| 20 years | £622.97 | £149,514 | £49,514 |
| 25 years | £545.67 | £163,700 | £63,700 |
| 30 years | £496.05 | £178,577 | £78,577 |
| 35 years | £462.17 | £194,112 | £94,112 |
The 35-year option is about £84 a month cheaper than the 25-year one, but pays roughly £30,000 more interest over the life of the loan — and that is per £100,000 borrowed, so it scales up with the mortgage. Which side of that trade-off suits a given buyer depends on their own circumstances.
Scaling it to a real purchase
The loan is the purchase price minus the deposit, so the deposit — not just the sticker price — sets the monthly cost. Take a home at Manchester's 2025 median of around £250,000 (HM Land Registry standard sales; you can see the true monthly cost of a Manchester postcode for M1 in the city centre):
| Deposit | Loan | Monthly (4.32%, 25 years) |
|---|---|---|
| 10% (£25,000) | £225,000 | £1,228 |
| 25% (£62,500) | £187,500 | £1,023 |
A bigger deposit shrinks the loan pound for pound, and with it the monthly payment — the £250 difference here comes entirely from the extra £37,500 deposit. Our guide to how much deposit you need walks through the loan-to-value bands.
You can rebuild any scenario from the per-£100,000 figures above, or set the price, deposit, rate and term directly in the mortgage repayment calculator. For single loan sizes we also break down the monthly cost of a £200,000 mortgage and the monthly cost of a £300,000 mortgage in full.
The rate you actually get
The 4.32% used throughout is the Bank of England's average quoted rate for a five-year fix at 75% loan-to-value — that is, for a buyer with a 25% deposit. It is a market benchmark, not the rate any one person will be offered. The rate on an individual mortgage depends on the lender, the size of the deposit, the length of the fix, the term and the borrower's credit profile; smaller deposits (higher loan-to-value) generally attract higher rates, and quoted rates change from month to month.
For context, the Bank's measure of the average rate actually being paid across all outstanding mortgages was 4.81% in June 2026 — higher than the latest quoted rate, because older and costlier fixes are still running. Lenders also apply an affordability assessment on top of the raw sum, under Financial Conduct Authority rules, testing whether repayments would remain manageable if rates or circumstances changed. The amount offered is often below what the arithmetic alone suggests.
What the payment doesn't cover
The mortgage is the largest monthly line for most buyers, but not the only one. Council tax, energy, buildings insurance and maintenance all sit on top — and, unlike the mortgage, barely move with the purchase price. Our true cost of buying a £250,000 home piece adds those lines up, and the wider set of cost-intelligence guides works through other price brackets.
Every payment figure here is derived from the standard amortisation of a level-payment repayment mortgage at the Bank of England's April 2026 quoted rate; the price context uses HM Land Registry Price Paid data, part of the open-data sources behind the Homecost guides.
This is general information, not financial advice. Mortgage rates and the amount you can borrow depend on your lender, deposit, term and credit profile. Speak to a qualified adviser before acting.