10.0% deposit · 90.0% LTV
Monthly mortgage payment: £1,501. Loan amount £270,000.
A £270,000 mortgage at 4.5% over 25 years works out at about £1,501 a month. Over the full term you'd pay £180,224 in interest — £451,223 in total.
Overpayment impact
| Minimum monthly payment | £1,500.75 |
| Monthly overpayment | +£200.00 |
| Total monthly outgoing | £1,700.75 |
Overpaying £200/month clears your mortgage 4 yr 10 mo sooner and saves £39,155 in interest. Many lenders cap penalty-free overpayments at 10% of the balance a year — check your deal.
Principal vs interest
If your rate rises
| Interest rate | Monthly payment | vs now |
|---|---|---|
| 4.5% (now) | £1,501 | — |
| 5.5% (+1) | £1,658 | +£157/mo |
| 6.5% (+2) | £1,823 | +£322/mo |
| 7.5% (+3) | £1,995 | +£495/mo |
What your monthly payment would become if you remortgaged onto a higher rate — e.g. when a fixed deal ends.
Balance over time
| Year | Interest | Principal | Balance |
| 1 | £12,028 | £5,981 | £264,019 |
| 6 | £10,522 | £7,487 | £229,729 |
| 11 | £8,636 | £9,373 | £186,805 |
| 16 | £6,276 | £11,733 | £133,073 |
| 21 | £3,322 | £14,687 | £65,812 |
| 25 | £431 | £17,578 | £0 |
How much can I borrow?
| Estimated borrowing (4–4.5× income) | £180,000 – £202,500 |
| Max property price with your £30,000 deposit | £232,500 |
A rough guide — most UK lenders cap borrowing at around 4.5× income. Your actual limit also depends on your outgoings, credit history and the lender's affordability stress test.
Upfront buying costs
| Deposit | £30,000 |
| SDLT (stamp duty) | £5,000 |
| Mortgage arrangement fee | £999 |
| Legal / conveyancing fees | £1,500 |
| Survey | £500 |
| Removal / moving costs | £1,200 |
| Total cash needed | £39,199 |
Stamp duty is estimated from your property price for the buyer type above. Legal, survey and moving costs are editable estimates — your actual quotes will vary.
Frequently asked questions
Is it worth overpaying my mortgage?
Overpaying comes straight off the balance, so you pay interest on a smaller debt and clear the loan sooner. It usually makes sense when your mortgage rate is higher than what you could earn (after tax) in savings, and once you have an emergency fund. Even small regular overpayments can save thousands in interest over the term.
How much interest could I save by overpaying?
It depends on your balance, rate and how early you overpay — the earlier in the term, the bigger the saving, because more of your payment is interest at the start. Enter a monthly overpayment or a lump sum above to see the exact interest saved and the years knocked off your term.
Are there limits or penalties on overpayments?
Many fixed-rate deals let you overpay up to 10% of the outstanding balance each year without penalty; above that you may pay an Early Repayment Charge (ERC). Always check your mortgage terms before making large overpayments, and consider whether reducing the term or the monthly payment suits you better.
Should I overpay the mortgage or pay into a pension?
Both reduce future costs, but pensions get tax relief and possible employer contributions, while overpaying gives a guaranteed “return” equal to your mortgage rate. Many people do some of each: secure the employer pension match first, keep an emergency fund, then overpay the mortgage with what’s left.
Related calculators & guides
Sources — official UK figures
This is an illustrative estimate assuming a constant interest rate over the full term. Real mortgages may have fixed and variable periods, arrangement fees, and rates that change. Your home may be repossessed if you do not keep up repayments. This is not financial advice — obtain a personalised mortgage illustration from a lender or broker.