Mortgage affordability & repayment
UK income multiples, monthly payments and rate scenarios.
Quick start — mortgage amount
How much can you borrow?
Typical borrowing (4.5× income)
£247,500
Max property price
£297,500
Some lenders stretch to 5× (£275,000) if income is over £75k or debt-free.
Monthly repayment
Loan £300,000 · LTV 86%
Monthly payment
£1,520
Total interest over term: £247,220
If the rate changes
Notes
- 4.5× income is the standard FCA/PRA cap. Lenders can lend 15% of new loans above 4.5×, so a small number stretch to 5–5.5× for high earners.
- LTV bands typically price at 60%, 75%, 80%, 85%, 90% and 95%. Crossing a band down can save 0.3–0.6% on the rate.
- Stress test: most lenders assume rate = product rate + 1% for affordability.
- This is an estimate. Speak to an FCA-authorised broker for a decision in principle.
How much does a £300,000 mortgage cost?
On a 25-year repayment mortgage at 4.5%, a £300,000 mortgage costs around £1,667 a month, with £200,249 of interest over the full term. The figures below update automatically for different rates, terms and deposit sizes.
Monthly repayments on a £300,000 mortgage
| Rate | 15 yrs | 20 yrs | 25 yrs | 30 yrs | 35 yrs |
|---|---|---|---|---|---|
| 4.0% | £2,219 | £1,818 | £1,584 | £1,432 | £1,328 |
| 4.5% | £2,295 | £1,898 | £1,667 | £1,520 | £1,420 |
| 5.0% | £2,372 | £1,980 | £1,754 | £1,610 | £1,514 |
| 5.5% | £2,451 | £2,064 | £1,842 | £1,703 | £1,611 |
| 6.0% | £2,532 | £2,149 | £1,933 | £1,799 | £1,711 |
Total interest on a £300,000 mortgage
- 15-year term at 4.5%£113,096 interest · £413,096 repaid
- 20-year term at 4.5%£155,508 interest · £455,508 repaid
- 25-year term at 4.5%£200,249 interest · £500,249 repaid
- 30-year term at 4.5%£247,220 interest · £547,220 repaid
- 35-year term at 4.5%£296,303 interest · £596,303 repaid
Shortening the term on a £300,000 mortgage from 35 to 25 years saves roughly £96,054 in interest.
Example scenarios for a £300,000 mortgage
- 5% deposit: buy at about £315,789 with a £15,789 deposit — 95% LTV, around £1,667/month at 4.5%.
- 10% deposit: buy at about £333,333 with a £33,333 deposit — 90% LTV, around £1,667/month at 4.5%.
- 15% deposit: buy at about £352,941 with a £52,941 deposit — 85% LTV, around £1,667/month at 4.5%.
- 25% deposit: buy at about £400,000 with a £100,000 deposit — 75% LTV, around £1,667/month at 4.5%.
- Income needed: most lenders cap at 4.5× income, so a £300,000 mortgage typically needs a household income of about £66,667.
- If rates rise 1%: repayments move from £1,667 to £1,842 a month — £175 more.
- Overpaying £100/month: on £300,000 at 4.5% you would clear the loan meaningfully earlier and cut interest — most lenders allow 10% overpayment a year penalty-free.
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A short guide to UK mortgages
Lenders decide what you can borrow on income multiples and affordability; the rate and term then decide what it costs each month.
- Most lenders cap borrowing at 4 to 4.5 times household income.
- A longer term lowers the monthly payment but raises total interest.
- A bigger deposit moves you into a cheaper loan to value band.
- Stress-test your payment 1–2 percentage points above today's rate.
Frequently asked questions
- How much can I borrow for a mortgage?
- Most UK lenders lend 4 to 4.5 times household income, subject to affordability checks on your outgoings, credit commitments and a stressed interest rate.
- How are monthly repayments calculated?
- A repayment mortgage spreads capital and interest over the term. Monthly cost rises with the loan size and rate, and falls as you extend the term — but a longer term means more total interest.
- Should I choose a 25 or 30 year term?
- A longer term lowers the monthly payment but increases total interest substantially. Many buyers start long for affordability and overpay later.
- What rate should I assume?
- Use a rate close to current market fixes and stress-test 1–2 percentage points higher so you know the payment still works at renewal.