UK Mortgage Calculator
Work out your UK mortgage payment and loan-to-value band, and see how monthly or lump-sum overpayments cut your term and interest.
Written by Rahman · Last reviewed
Quick answer
A UK mortgage payment depends on the loan-to-value (LTV) band it falls into as much as the rate itself: lenders price in bands (commonly up to 60%, 75%, 85%, 90% and 95%), so a deposit that crosses a band boundary can earn a noticeably cheaper rate. On a £300,000 property with a £60,000 (20%) deposit (an 80% LTV, priced in the "up to 85%" band), a 25-year repayment mortgage at 5.5% costs £1,473.81 a month and £202,142.99 in total interest; the same loan interest-only costs £1,100.00 a month but never reduces the balance on its own.
| Year | Principal paid | Interest paid | Balance |
|---|---|---|---|
| 1 | 4,600.54 | 13,085.18 | 235,399.46 |
| 2 | 4,860.05 | 12,825.67 | 230,539.41 |
| 3 | 5,134.19 | 12,551.53 | 225,405.21 |
| 4 | 5,423.80 | 12,261.92 | 219,981.41 |
| 5 | 5,729.75 | 11,955.97 | 214,251.66 |
| 6 | 6,052.95 | 11,632.77 | 208,198.71 |
| 7 | 6,394.39 | 11,291.33 | 201,804.32 |
| 8 | 6,755.08 | 10,930.64 | 195,049.24 |
| 9 | 7,136.12 | 10,549.60 | 187,913.13 |
| 10 | 7,538.65 | 10,147.07 | 180,374.47 |
| 11 | 7,963.89 | 9,721.83 | 172,410.58 |
| 12 | 8,413.12 | 9,272.60 | 163,997.47 |
| 13 | 8,887.68 | 8,798.04 | 155,109.78 |
| 14 | 9,389.02 | 8,296.70 | 145,720.76 |
| 15 | 9,918.63 | 7,767.09 | 135,802.13 |
| 16 | 10,478.12 | 7,207.60 | 125,324.01 |
| 17 | 11,069.17 | 6,616.55 | 114,254.84 |
| 18 | 11,693.56 | 5,992.16 | 102,561.28 |
| 19 | 12,353.17 | 5,332.55 | 90,208.11 |
| 20 | 13,049.98 | 4,635.74 | 77,158.13 |
| 21 | 13,786.10 | 3,899.62 | 63,372.03 |
| 22 | 14,563.75 | 3,121.97 | 48,808.28 |
| 23 | 15,385.26 | 2,300.46 | 33,423.02 |
| 24 | 16,253.11 | 1,432.61 | 17,169.91 |
| 25 | 17,169.91 | 515.81 | 0.00 |
Total interest over 25 years: 202,142.99. The CSV has one row per month.
A one-off lump sum is modelled as paid at the start, reducing the loan before the schedule begins; a monthly overpayment reduces the term and total interest instead. Many lenders let you overpay up to 10% of the balance each year without an early repayment charge (ERC) — a common allowance, not a universal one, so check your specific mortgage offer. Estimate the stamp duty on this price →
Results are estimates for general guidance and are not financial, tax or legal advice. Except where a calculator names a currency, figures carry no currency of their own: put in pounds and you get pounds back, put in rupees and you get rupees. Figures depend on the assumptions you enter and on rates that change over time. Check current rates and speak to a qualified adviser before acting on them.
About the UK Mortgage Calculator
A UK mortgage is priced on two things together: the interest rate itself, and the loan-to-value (LTV) band your deposit places you in. Lenders publish rate tables in bands (commonly up to 60%, 75%, 85%, 90% and 95% LTV), so a deposit just over a band boundary is often worth a noticeably better rate than one just under it.
This calculator works out your loan amount and LTV band from a property price and deposit, then estimates the monthly payment for either a repayment or interest-only mortgage, with optional monthly or one-off lump-sum overpayments.
Repayment: standard amortising payment on the loan over the term, same formula as any amortising loan. Interest-only: payment = loan × monthly rate, and the loan balance itself never reduces without a separate repayment vehicle or an overpayment.
A one-off lump sum is modelled as paid at the start, reducing the loan before the payment is calculated; a monthly overpayment (repayment mode only) reduces the term and total interest instead, the same mechanism as the Mortgage and Loan Payment calculators.
The 2-year and 5-year fix cliff edge
Most UK mortgages are not fixed for the whole term: they carry an initial fixed-rate deal, commonly 2 or 5 years, after which the mortgage reverts to the lender's standard variable rate (SVR) unless you remortgage or switch product first. The SVR is typically several percentage points above the fixed rate that preceded it, so the payment jump at the end of a fix can be substantial if nothing is done about it.
Product fees (an arrangement or product fee, commonly £0–£2,000) are charged on most fixed deals, either paid upfront or added to the loan. Adding it to the loan means paying interest on the fee itself for the rest of the term, so comparing deals on rate alone, ignoring the fee, can favour the wrong product.
- Set a reminder several months before a fix ends: remortgaging or switching product before reverting to SVR avoids the jump entirely.
- A larger fee sometimes buys a meaningfully lower rate; compare the total cost over the fixed period, not the fee or the rate in isolation.
- Early repayment charges (ERCs) typically apply if you leave a fixed deal early, which is a separate cost from the standard overpayment allowance below.
Affordability is still assessed, just not by a single Bank of England formula
The Bank of England withdrew its specific mandated affordability stress test (a fixed stress interest rate lenders had to test against) from 1 August 2022. That did not remove affordability checks: the separate loan-to-income "flow limit", which caps how many mortgages a lender can extend at 4.5× income or more, remains in place, and the FCA's own responsible-lending rules still require lenders to verify income and stress-test affordability against their own methodology.
In practice this means each lender sets its own stress rate and income multiple rather than following one fixed national formula, so the amount two lenders will offer the same borrower can differ meaningfully, so it is worth shopping around for, not just comparing headline rates.
Frequently Asked Questions
Why does my LTV band matter more than my exact deposit percentage?
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Lenders price in bands rather than a smooth curve, so an 79% LTV and an 81% LTV can sit in different pricing tiers even though the deposit difference is small. Finding a slightly larger deposit to cross into a cheaper band can be worth more than the extra deposit itself.
What is the difference between repayment and interest-only?
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A repayment mortgage pays down both interest and principal each month, so the balance reaches zero at the end of the term. An interest-only mortgage pays only the interest: the balance never reduces on its own, and you need a separate plan (savings, investments, or sale of the property) to repay it at the end.
How much can I overpay without a penalty?
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Many lenders allow overpayments up to 10% of the outstanding balance per year without an early repayment charge (ERC), but this is a common allowance, not a universal one, and some deals set a different limit or none at all. Check your specific mortgage offer before overpaying beyond the amount you have confirmed is free.
Does the Bank of England still stress-test mortgage affordability?
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The Bank of England withdrew its own mandated stress-rate formula in August 2022. Lenders still assess affordability, including their own stress test, under the FCA's Mortgage Conduct of Business rules, and a separate loan-to-income flow limit (capping loans at 4.5x income or more) remains in place.
Sources
- Bank of England — Financial Policy Committee confirms withdrawal of mortgage market affordability test — Confirms the Bank of England withdrew its mandated stress-interest-rate formula in August 2022; the loan-to-income flow limit was not withdrawn, and lenders still assess affordability under the FCA's own MCOB rules.