Mortgage repayments by amount

Repayments on a £300,000 Mortgage

A £300,000 mortgage costs about £1,667.50 a month at 4.5% over 25 years, with roughly £200,249 of interest across the term. Change the rate and term below for your own figure.

Free, no signup4.5% over 25 yearsTotal interest shown

Monthly repayment

£1,667.50

a month on a £300,000 mortgage at 4.5% over 25 years

Amount borrowed	£300,000
Monthly repayment	£1,667.50
Total interest	£200,249
Total repayable	£500,249

At 4.5% over 25 years, a £300,000 repayment mortgage is about £1,667.50 a month. Over the full term you repay roughly £500,249, of which about £200,249 is interest.

Representative estimate at 4.5% over 25 years, repayment basis, paid monthly. Excludes fees and assumes a single rate for the whole term. Not financial advice.

Simon Chadwick

Founder, Orbit Money

Method: standard amortisation formulaUpdated: 17 July 2026Sources: MoneyHelper, Bank of England

What a £300,000 mortgage costs each month

On a £300,000 repayment mortgage at 4.5% over 25 years, the monthly payment works out at about £1,667.50. Each payment covers the interest on the balance for that month, and the rest comes off the capital, so the amount you owe falls a little further every month until it reaches zero at the end of the term. Across the full 25 years you repay roughly £500,249, which is the £300,000 you borrowed plus about £200,249 of interest.

How the rate changes your £300,000 repayment

The interest rate moves the payment more than anything else. Here is the monthly repayment on a £300,000 mortgage over 25 years at a range of rates, so you can see where your own deal would land.

Interest rate	Monthly repayment	Total interest
3.5%	£1,501.87	£150,561
4%	£1,583.51	£175,053
4.5%	£1,667.50	£200,249
5%	£1,753.77	£226,131
5.5%	£1,842.26	£252,679
6%	£1,932.90	£279,871

Try your own rate and term

The calculator below is set to £300,000. Change the rate, the term or the repayment frequency to match your mortgage, or switch to interest-only to compare. It shows the monthly payment, the total interest and the total repaid, and the balance falling over the life of the loan.

Your mortgage

Work out from

Loan amount

How much you're borrowing

Interest rate

Your annual rate (% APR)

Mortgage term

Most UK mortgages run 25 to 30 years

yrs

Repayment frequency

Mortgage type

Your repayment

£1,667.50/month

Repayment mortgage over 25 years£200,249 total interest

Repayment (capital & interest): the balance falls to zero over the term.

Amount borrowed£300,000

Repayment per month£1,667.50

Number of repayments300

Total interest£200,249

Total repaidCapital plus interest over the full term£500,249

Repayment by frequency

Frequency	Repayment	Total interest
monthly	£1,667.50	£200,249
fortnightly	£769.19	£199,977
weekly	£384.51	£199,860

Each frequency is worked out on its own true period, so fortnightly is not the monthly figure halved. Most UK lenders collect monthly, though some allow weekly or fortnightly.

Want to clear it sooner?

Overpaying, even a small amount each month, comes straight off the capital and cuts the interest on every payment after it. See the effect with the mortgage overpayment calculator.

Estimate only. Assumes a fixed rate for the full term and excludes fees, product changes and rate changes. A guide, not financial advice.

Frequently asked questions

What are the monthly repayments on a £300,000 mortgage?

On a £300,000 repayment mortgage at 4.5% over 25 years, the monthly payment is about £1,667.50. The exact figure depends on your interest rate and term, so use the calculator below to try your own numbers. This is capital and interest, so the balance clears by the end of the term.

How much interest do you pay on a £300,000 mortgage?

A £300,000 mortgage at 4.5% over 25 years costs roughly £200,249 in interest across the full term, on top of the £300,000 you borrowed. That makes the total repayable about £500,249. A lower rate or a shorter term cuts the interest sharply.

Does a longer term lower the repayments on a £300,000 mortgage?

Yes. At 4.5%, a £300,000 mortgage over 25 years is about £1,667.50 a month, over 30 years about £1,520.06, and over 35 years about £1,419.77. The longer term lowers the monthly payment but you pay interest for longer, so the total cost is higher.

What rate is used for these £300,000 mortgage figures?

The headline figures assume 4.5% over 25 years, paid monthly, on a repayment basis. That is a representative rate, not a quote. Rates move with the market and with your deposit, so put your own rate and term into the calculator for a figure that fits your deal.

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About the author

Simon Chadwick

Founder of Orbit Money

Simon is the founder of Orbit Money, a tool that helps people track subscriptions and recurring spend. He builds Orbit's free money calculators and writes about personal finance for UK and Australian readers.