Let's work out your mortgage.
Your monthly mortgage depends on the price, your deposit, the interest rate and the term. As a guide, a £290,000 home with a 10% deposit over 25 years at 4.5% costs about £1,450 a month on a repayment basis, and UK lenders typically cap borrowing at around 4.5× your income. The tools below let you model payment type, affordability, government schemes and overpayments for any property.
Last reviewed · figures use 2025/26 UK rates.
We'll move through the key questions in plain English — what you'll pay, what you'll repay, and how exposed you are to rate changes. Tweak any input on the right and the answers update.
Download PDF report →Before we start — three things you might need.
We've vetted these. Take or leave.
True Bricks may earn a commission from these links at no cost to you.
Are you paying down the loan, or just the interest?
We're showing repayment figures — your monthly payment covers both interest and a chunk of capital, so the loan actually shrinks.
So what would you pay each month?
£1,654
Monthly paymentFor every month for the next 25 years, against a £297,500 loan at 4.5%. That's about 47% of a £3,500 take-home — around the 50% rule most lenders apply.
And what does that add up to, in total?
£297,500
borrowed today£496,080
paid back over 25 years£198,580
of that is pure interestPut plainly: you'll pay back roughly 67% extra on top of what you borrow. That's the cost of buying with a mortgage rather than cash.
Will a lender actually give you this much?
On a typical 4.5× income multiple, you'd need to earn at least £66,111 a year for this to clear underwriting. Your inputs put household income at £42,000 — about £24,111 short of the standard cut-off.
Want to look closer? Here are four questions worth asking.
Your situation
Drag to tweak85.0% loan-to-value
We compute live. Move any slider and the answers in the column on the left update.
Deep dive · 01 · Remaining balance
How much will I owe in five years?
£261,377
Five years in, you'd have paid down about £36,123 of the £297,500 loan — roughly 12% of the capital. Most of your monthly payment in the early years goes on interest, not principal.
Outstanding balance over the 25-year term
And in ten years?
£216,159
Ten years in you'd still owe £216,159 — only 27% of capital paid down. The curve really steepens after year 15 or so, when each pound starts going further against principal.
When do I cross the halfway mark?
Year 16
You cross it just after your 16-year mark — earlier than you'd expect on a 25-year term, because interest is heavier early on and capital catches up exponentially.
One way to bring these numbers down
Overpaying by even £100/mo shaves roughly 2 years 5 months off a repayment term — see the Overpayment tab for the full picture.
Deep dive · 02 · Capital vs interest
Am I paying down the loan or just paying interest?
Annual payment split over the 25-year term
In year one, just £6,591 of your £19,843 annual payment goes on the loan — the rest is interest. By year 16, the split flips. By year 25, your final payments are almost all capital.
Deep dive · 03 · Scenario comparison
What if I changed something?
| Metric | Current | Shorter term (20y) | Bigger deposit (+£10k) | Lower rate (-0.5%) |
|---|---|---|---|---|
| Monthly | £1,654 | £1,882 | £1,598 | £1,570 |
| Loan | £297,500 | £297,500 | £287,500 | £297,500 |
| Total repaid | £496,080 | £451,712 | £479,406 | £471,094 |
| Interest | £198,580 | £154,212 | £191,906 | £173,594 |
| Income needed (4.5×) | £66,111 | £66,111 | £63,889 | £66,111 |
The shorter-term scenario costs £229 more per month but saves you £44,369 in interest over the loan's life. The bigger-deposit scenario saves £56 monthly and £6,675 in interest. The lower-rate scenario assumes you secure a 0.5%-better deal — realistic if your credit profile is strong or you're remortgaging.
Deep dive · 04 · Rate stress test
What happens if rates rise before I'm fixed?
You're modelling against a 4.5% rate today. Most UK borrowers fix for 2 or 5 years — when that deal rolls off, the rate you remortgage onto is the open question. Here's the same £297,500 loan at three plausible rate steps.
Your baseline. Around the middle of the 50% affordability rule.
+£173 a month, +£2,080 a year. Now eating 52% of your take-home.
+£355 a month, +£4,262 a year. Now eating 57% of your take-home.
+£545 a month, +£6,539 a year. At this point you'd be paying 33% more than today and may need to lengthen the term or revisit the deposit.
What's the simplest way to cap this risk?
A 5-year fixed deal locks today's 4.5% until 2031. If rates settle 1% higher than today, you'd save £10,399 over those five years. The trade-off: you can't benefit if rates fall.
What if my income hasn't kept up?
On +3%, this mortgage would need household income of around £66,111 on a 4.5× multiple to pass underwriting again. We'd flag this scenario for an early conversation with a broker.
Frequently asked
How much mortgage can I afford in the UK?
Most lenders cap borrowing at around 4.5 times your annual income, though affordability also depends on your outgoings, deposit and the interest rate. On a £40,000 salary that's roughly £180,000 — use the affordability tool to model your own numbers.
What will my monthly mortgage payment be?
It depends on the loan size, rate and term. As a guide, a £261,000 repayment mortgage (a £290,000 home with a 10% deposit) over 25 years at 4.5% costs about £1,450 a month. Interest-only is lower but never clears the balance.
How much deposit do I need to buy a home?
Usually a minimum of 5%, but 10–15% unlocks noticeably better interest rates and lower monthly payments. A larger deposit also reduces the total interest you pay over the life of the loan.
Does overpaying my mortgage actually save money?
Yes — overpayments come straight off the capital, so they cut both the interest you pay and the term. Even small regular overpayments can save thousands; the overpayment tool shows the saving for your loan.