£300,000 Mortgage: Monthly Payment Over 25 Years at 4.5%
A £300,000 mortgage at 4.5% over 25 years costs £1,667 a month in principal and interest. Over the full term you would repay £500,249, of which £200,249 is interest, about 67% of the amount borrowed.
That payment is for an example rate. At 3.5% it would be £1,502 and at 5.5% it would be £1,842, so each percentage point moves the payment by roughly £170 a month.
Updated October 2026
- Monthly payment £1,667 principal and interest
- Total interest £200,249 67% of the loan
- Total repaid £500,249
- Amount borrowed £300,000
Change the numbers
The calculator below opens with this example filled in. Edit any value to see your own figures, or open the full UK Mortgage Calculator.
Property Details
Deposit: £75,000 · Loan: £300,000
Example rate, not a quote
Monthly Payment
£1,667
Loan Amount: £300,000
Principal
£300,000
Total Interest
£200,249
Total Payment
£500,249
Principal + Interest
£1,667/mo
Tax + Insurance
£0/mo
Stamp duty (England & Northern Ireland)
Stamp Duty Land Tax: £8,750 (2.33% of the price). Cash needed up front, deposit plus stamp duty: £83,750.
Buying in Scotland or Wales? Those nations charge different taxes (LBTT and LTT): see Revenue Scotland or the Welsh Government.
Rates: GOV.UK, checked 23 October 2026. Conveyancing and other costs are not included.
Year-by-Year Amortization
| Year | Principal | Interest | Balance |
|---|---|---|---|
| 1 | £6,646 | £13,364 | £293,354 |
| 2 | £6,951 | £13,059 | £286,403 |
| 3 | £7,271 | £12,739 | £279,132 |
| 4 | £7,605 | £12,405 | £271,528 |
| 5 | £7,954 | £12,056 | £263,574 |
| 6 | £8,319 | £11,691 | £255,254 |
| 7 | £8,702 | £11,308 | £246,553 |
| 8 | £9,101 | £10,909 | £237,452 |
| 9 | £9,519 | £10,491 | £227,932 |
| 10 | £9,957 | £10,053 | £217,975 |
| 11 | £10,414 | £9,596 | £207,561 |
| 12 | £10,893 | £9,117 | £196,669 |
| 13 | £11,393 | £8,617 | £185,276 |
| 14 | £11,916 | £8,094 | £173,359 |
| 15 | £12,464 | £7,546 | £160,896 |
| 16 | £13,036 | £6,974 | £147,859 |
| 17 | £13,635 | £6,375 | £134,224 |
| 18 | £14,262 | £5,748 | £119,962 |
| 19 | £14,917 | £5,093 | £105,046 |
| 20 | £15,602 | £4,408 | £89,444 |
| 21 | £16,319 | £3,691 | £73,125 |
| 22 | £17,069 | £2,941 | £56,056 |
| 23 | £17,853 | £2,157 | £38,203 |
| 24 | £18,673 | £1,337 | £19,531 |
| 25 | £19,531 | £479 | £0 |
What changes a £300,000 payment
Rate and term do most of the work. At 25 years, moving the rate by half a point changes the payment by about £86 a month up or £84 down. Shortening the term raises the payment but removes a lot of interest: 20 years at 4.5% is £1,898 a month and £155,508 in interest, against £1,520 and £247,220 over 30 years.
| Interest rate | 20 years | 25 years | 30 years |
|---|---|---|---|
| 3.5% | £1,740 (£117,571 interest) | £1,502 (£150,561 interest) | £1,347 (£184,968 interest) |
| 4% | £1,818 (£136,306 interest) | £1,584 (£175,053 interest) | £1,432 (£215,609 interest) |
| 4.5% | £1,898 (£155,508 interest) | £1,667 (£200,249 interest) | £1,520 (£247,220 interest) |
| 5% | £1,980 (£175,168 interest) | £1,754 (£226,131 interest) | £1,610 (£279,767 interest) |
| 5.5% | £2,064 (£195,279 interest) | £1,842 (£252,679 interest) | £1,703 (£313,212 interest) |
Monthly payment, with total interest in brackets.
Where each payment goes
In the first year, £13,364 of your payments is interest and only £6,646 reduces the loan, so interest is 67% of what you pay. The principal part of the payment overtakes the interest part in month 116 (year 10). After 5 years you have repaid £36,426, which is 12.1% of the loan, and you still owe £263,574. Half the loan is gone by month 191.
| End of year | Principal paid | Interest paid | Balance left |
|---|---|---|---|
| 1 | £6,646 | £13,364 | £293,354 |
| 2 | £6,951 | £13,059 | £286,403 |
| 3 | £7,271 | £12,739 | £279,132 |
| 5 | £7,954 | £12,056 | £263,574 |
| 10 | £9,957 | £10,053 | £217,975 |
| 15 | £12,464 | £7,546 | £160,896 |
| 20 | £15,602 | £4,408 | £89,444 |
| 25 | £19,531 | £479 | £0 |
Principal and interest paid during each year shown, and the balance at the end of it.
Deposit and stamp duty on the home you are buying
A £300,000 mortgage is a loan, not a price. With a 20% deposit it buys a £375,000 home; a bigger deposit lowers the price you need to reach, a smaller one raises it. Stamp Duty Land Tax (England and Northern Ireland) is charged on the price, not the loan: on £375,000 it is £8,750 for a home mover, £3,750 for a first-time buyer and £27,500 for an additional property. The last column adds the deposit and the standard-rate stamp duty, the cash you need before costs such as legal fees. Rates checked 23 October 2026 on GOV.UK; Scotland and Wales have their own taxes.
| Deposit | Home price | Deposit amount | Stamp duty: home mover | First-time buyer | Additional property | Cash up front (home mover) |
|---|---|---|---|---|---|---|
| 10% | £333,333 | £33,333 | £6,667 | £1,667 | £23,333 | £40,000 |
| 15% | £352,941 | £52,941 | £7,647 | £2,647 | £25,294 | £60,588 |
| 20% | £375,000 | £75,000 | £8,750 | £3,750 | £27,500 | £83,750 |
| 25% | £400,000 | £100,000 | £10,000 | £5,000 | £30,000 | £110,000 |
Stamp duty and cash up front for a £300,000 loan at different deposits.
Before you rely on these numbers
- The 4.5% rate is an example. Rates change often and depend on your deposit, credit and lender, so use the rate on an actual quote.
- Fees such as arrangement, valuation and legal costs are not included. When a fixed or discounted deal ends the rate changes, so re-run the calculator with the new rate and your remaining term.
- This is general information, not a quote or financial advice.
Common questions
What is the monthly payment on a £300,000 mortgage?
£1,667 a month in principal and interest at 4.5% over 25 years. At 3.5% it is £1,502 and at 5.5% it is £1,842. Use the rate you are actually offered.
How much interest will I pay on a £300,000 mortgage?
£200,249 over 25 years at 4.5%, which is 67% of the amount borrowed. A 20-year term cuts it to £155,508 but raises the payment to £1,898.
How much would I save by paying £150 extra a month?
About £31,713 in interest, and the loan would be repaid 3 years 6 months early. Check that your lender allows overpayments or extra principal payments without a penalty.
How much stamp duty will I pay with a £300,000 mortgage?
It depends on the price of the home, not the loan. With a 20% deposit the home costs £375,000, and stamp duty in England and Northern Ireland is £8,750 for a home mover, £3,750 for a first-time buyer and £27,500 for an additional property (rates checked 23 October 2026).
What deposit do I need for a £300,000 mortgage?
Lenders set their own minimum. With a 10% deposit the home costs £333,333, with 15% £352,941, with 20% £375,000 and with 25% £400,000. A larger deposit lowers the loan-to-value, which usually gets a lower rate.