How the repayments are worked out
Repayment mortgages use the standard annuity formula, which spreads capital and interest into equal monthly payments:
Monthly payment = loan × r ÷ (1 − (1 + r)−n)
r = annual rate ÷ 12, n = years × 12
For £150,000 at 4.5% over 25 years: r = 0.00375 and n = 300, giving £833.75 a month. Over the full term you repay £250,125, so the interest comes to £100,125.
Interest-only
On interest-only you pay just the interest: £150,000 × 4.5% ÷ 12 = £562 a month. It is cheaper each month, but the £150,000 is still owed at the end, so lenders want a repayment plan.
Income you would need
Lenders usually cap borrowing at about 4 to 4.5 times income, with some going to 5 or 5.5 times for higher earners. To borrow £150,000 you would typically need a household income of £33,333 to £37,500. Check your figures with the mortgage affordability calculator.
Buying a home? Add the stamp duty to your budget, and see how much overpaying could save.
Frequently asked questions
How much is a £150,000 mortgage a month?
A £150,000 repayment mortgage costs about £834 a month over 25 years at 4.5% interest, £760 over 30 years and £710 over 35 years.
What salary do I need for a £150,000 mortgage?
Most UK lenders lend around 4 to 4.5 times income, so a £150,000 mortgage usually needs a household income of about £33,333 to £37,500 a year, depending on your debts and outgoings.
How much interest will I pay on a £150,000 mortgage?
At 4.5% over 25 years you would repay £250,125 in total, of which £100,125 is interest. A shorter term or a lower rate cuts this.
How much is a £150,000 interest-only mortgage a month?
At 4.5%, interest-only payments on £150,000 are about £562 a month, but you still owe the full £150,000 at the end of the term.
Last reviewed October 2026. Example rates only; your lender's rate, fees and term decide what you actually pay.