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Tax year 2026/27 · Rest of UK · annual

Mortgage Calculator UK

Monthly repayments and total interest for any UK mortgage.

Tax year

Region

Schedule

Your details

Loan amount

Interest rate

4.5%

Term (years)

Monthly payment

£1,112

25 years · 4.50% interest

Where your money goes

Loan £200,000Interest £133,499

Totals

Monthly payment	£1,112
Total interest over 25 years	£133,499
Total repaid	£333,499

Interactive scenarios

Tax and deductions, your way

Tax year

Region

Pay schedule

Salary £45,000

Net (monthly)

£2,806

Income tax (monthly)

£541

NI (monthly)

£216

Effective rate

20.2%

Modelled on a 5% pension. Showing monthly figures, rest of UK, tax year 2026/27.

The full guide

Everything worth knowing about Mortgage

Worked examples with real figures, the rules underneath the number, and the traps that catch people out.

Mortgage calculator UK: your monthly payment, explained

A UK mortgage calculator turns a loan amount, an interest rate and a term into a monthly repayment. Borrow £240,000 over 25 years at 4.5% and the payment is £1,334 a month, with £160,199 of interest paid across the term. Change any one of the three inputs and the sections below show what moves.

Most buyers fixate on the monthly figure. The total cost matters just as much, because the cheapest month and the cheapest mortgage are rarely the same deal, and the difference runs into tens of thousands of pounds over a full term.

The payment is the headline. The interest is the story.

How a monthly mortgage payment is calculated

A repayment mortgage charges interest on the balance you still owe, then bundles interest and capital into one fixed monthly payment. The lender sets that payment so the balance reaches exactly zero on the final month of the term, using the rate, the loan and the number of payments.

Early payments are mostly interest because the balance is at its largest. On £240,000 at 4.5%, the first month carries £900 of interest against the £1,334 payment, so only £434 comes off the debt. Halfway through the term the balance has fallen to roughly £153,000, so the interest share shrinks and the capital share grows with every payment after that.

UK lenders typically calculate interest daily and charge it monthly, so making the payment early in the month and overpaying straight after a payment lands both trim a little extra interest. Interest only mortgages skip the capital entirely, leaving the full loan standing at the end of the term; the calculator above models the repayment route, which is the default for residential buyers.

Part and part mortgages split the loan between a repayment slice and an interest only slice. The payment sits between the two pure forms, and the interest only slice still needs a repayment plan at the end, so lenders treat it as a separate risk and ask for evidence of how it will be cleared.

Where each pound goes

Capital versus interest across the term

Capital repaid£240,000
Interest paid£160,199
£240,000 borrowed over 25 years at 4.5% costs £400,199 in total.

£240,000 over 25 years at 4.5%: where the money goes

The monthly payment is £1,334. In month one, £900 of it is interest and £434 reduces the balance. By the final year the split has flipped, and almost every pound of the payment reduces the debt instead.

Across 300 payments you hand over £400,199 in total. The borrowing accounts for £240,000 of that and interest accounts for £160,199, which is why the rate and the term deserve as much attention as the purchase price when you compare deals.

The term: stretching the loan cuts the payment and raises the bill

Hold the loan and the rate steady at £240,000 and 4.5%, then move only the term. Over 20 years the payment is £1,518 a month and total interest comes to £124,406. Over 25 years the payment drops to £1,334 and interest climbs to £160,199. Over 30 years the payment falls to £1,216, but interest reaches £197,776.

Five extra years between the 25 and 30 year terms save £118 a month and cost £37,577 in extra interest. Lenders push longer terms because affordability checks pass more easily on smaller payments, not because the longer deal is better for the borrower.

The practical middle ground is a longer term taken for flexibility with planned overpayments on top. That behaves like a shorter term whenever your budget allows and relaxes in the months when it does not.

Lenders also cap the term by age, commonly requiring the mortgage to end before the borrower reaches their 70th or 75th birthday unless pension income supports a later finish. A term that runs past retirement needs evidence of income in retirement, which is why the longest terms are easiest to obtain in your twenties and thirties.

Term comparison

The same loan over 20, 25 and 30 years

20 years · £1,518/mo

£124,406 interest

25 years · £1,334/mo

£160,199 interest

30 years · £1,216/mo

£197,776 interest

Same loan, same rate: the shorter term costs more each month and far less overall.

Deposit and loan to value: the rate you are offered

Lenders price risk in loan to value steps, so the size of your deposit decides which shelf of rates you shop from. On a £300,000 home, a 10% deposit means borrowing £270,000 at 90% loan to value. A 25% deposit means borrowing £225,000 at 75%, where rates are visibly cheaper.

Illustrative rates make the gap concrete. At 4.79%, the £270,000 loan costs £1,546 a month and £193,661 of interest over 25 years. At 4.29%, the £225,000 loan costs £1,224 a month and £142,187 of interest. The bigger deposit saves on the loan size and on the rate at the same time, a double win worth roughly £51,000 of interest across the term.

Crossing a loan to value boundary mid term matters too. Remortgaging once your balance falls below 80% or 75% of the current value can unlock a cheaper shelf of products, which is why the calculator is worth rerunning before every product switch.

Deposits gifted by family work within the same structure. Lenders accept a gifted deposit with a signed declaration that the money is a gift rather than a loan, and the gift lifts you into a lower loan to value band in exactly the same way as savings do.

Fixed rate or tracker: certainty against movement

A fixed rate holds your payment steady for two, three, five or ten years, whatever the Bank of England does. A tracker follows the base rate up and down, usually with no early repayment charge, so the payment you start with is not the payment you keep.

On £240,000, a half point rise in the rate adds roughly £69 a month to a repayment mortgage in its early years. Fixing buys immunity from that movement; tracking buys freedom to overpay, move house or leave the deal without a penalty.

Most UK buyers fix for two or five years and accept the product fee as the price of certainty. The right answer depends on how much slack your monthly budget carries, not on an interest rate forecast that nobody can make reliably.

Product fees and the rate after your deal ends

The headline rate is not the whole price of a deal. Arrangement and product fees commonly run from nothing to about £1,500, and adding a £999 fee to the loan means repaying roughly £1,666 across a 25 year term at 4.5%, so the fee itself quietly costs about £667 of interest. Paying the fee upfront, or choosing a slightly higher rate with no fee on a smaller loan, often works out cheaper.

Cashback deals invert the same sums. A few hundred pounds back at completion rarely compensates for a higher rate held for five years on a large balance, which is why the calculator's total interest figure beats the marketing line every time.

The second price nobody quotes is the standard variable rate your deal reverts to when the fixed or tracker period ends. That rate is usually far above the deal rate, and each month spent drifting on it hands back the savings the deal created. Note the end date when you sign, and start the remortgage conversation three to six months before it arrives.

Overpayments: the cheapest improvement you can make

Add £200 a month to the £240,000 example at 4.5% and the mortgage clears in 19 years and 9 months instead of 25 years. Total interest falls from £160,199 to £122,123, a saving of £38,076, and you own the home outright more than five years early.

Most fixed products allow overpayments of up to 10% of the balance each year without charge, and tracker and offset deals often allow unlimited amounts. Check the allowance before you pay, because an early repayment charge on the excess can erase the saving.

Overpaying beats a savings account whenever your mortgage rate exceeds the after tax rate you can earn on deposits, which is most of the time. The trade is flexibility: money paid into the mortgage is hard to pull back out in an emergency, so keep a cash buffer outside it first.

An offset mortgage answers that flexibility problem. Savings held in a linked account reduce the balance you pay interest on without reducing the loan itself, so £20,000 held against the £240,000 loan means interest on £220,000 while the cash stays available. The effect matches overpaying while the money sits there, and reverses the moment you spend it.

Affordability is not the payment: what lenders actually test

The calculator shows what a mortgage costs. A lender decides what you may borrow using an income multiple, commonly around four and a half times gross income, then stress tests the payment at a rate well above the product rate to check you could cope with rises.

That is why a payment that looks comfortable can still come with a smaller offer than expected. Committed spending, childcare costs, existing debts and the length of the term all feed the affordability model alongside the headline salary.

Run the payment here first, then treat the lender's figure as a separate question. Knowing both numbers before you view houses stops you building an offer on a loan nobody will approve.

Self employed applicants meet the same test with different evidence. Most lenders average the last two or three years of declared income from tax returns or accounts, and a single strong year rarely carries the application on its own. Company directors may find lenders who count retained profits alongside salary and dividends, which can lift the offer without lifting the payment.

Joint applications combine both incomes before the multiple applies, which is the main reason two applicants can usually borrow more than one. Every applicant also brings their own commitments into the model, so a second income with heavy debts attached adds less than the headline salary suggests.

Where the Mortgage Calculator UK gets its figures

Rates, bands and thresholds follow published HMRC and gov.uk figures for the 2026/27 tax year, held in one table that every tool reads. April arrives, the table changes, and the results move together.

Earlier years stay available through the year selector, so a late self assessment runs on the numbers that applied at the time rather than today's.

Some cases still need an accountant. K codes carrying negative allowances, bespoke sacrifice arrangements, the annual allowance taper for very high earners, and anything involving two employments at once.

About this calculator

The UK Mortgage Calculator works out your monthly repayment for a capital-and-interest mortgage, plus the total interest you will pay over the full term.

Frequently asked questions

How is my monthly mortgage payment calculated?+

Lenders use the standard repayment formula: the loan amount multiplied by the monthly interest rate, scaled over the number of payments. Our calculator applies the exact formula M = P[r(1+r)^n]/[(1+r)^n-1], so the figure matches what a lender quotes for a capital-and-interest mortgage.

How much will a £200,000 mortgage cost per month?+

At 4.5% over 25 years, a £200,000 repayment mortgage costs about £1,112 a month, with roughly £133,500 of total interest. Stretch the term to 35 years and the payment drops to around £933, but total interest rises to about £192,000. Small rate changes move these numbers a lot.

Repayment or interest-only: which is better?+

Repayment mortgages clear the debt by the end of the term and suit almost all homebuyers. Interest-only is cheaper month to month but leaves the full loan to repay at the end, so lenders demand a credible repayment plan. Most residential borrowers should choose repayment.

Does a longer mortgage term save money?+

A longer term cuts the monthly payment but increases the total interest you pay, sometimes dramatically. A £200,000 loan at 4.5% costs about £133,500 in interest over 25 years but £192,000 over 35 years. Only extend the term if you need the lower payment to pass affordability.

What happens when my fixed rate ends?+

You move onto the lender's standard variable rate unless you remortgage to a new deal. The SVR is usually much higher than fixed rates, so most borrowers remortgage a few months before the fixed term ends. Our calculator lets you model the payment at different rates to prepare.

Should I overpay my mortgage?+

Overpaying cuts the interest you pay and can shave years off the term, but check your lender's overpayment allowance first, usually 10% of the balance per year without penalty. Compare the mortgage rate against what your savings earn: if the mortgage rate is higher, overpaying usually wins.

How accurate is this mortgage calculator?+

The maths matches lender repayment calculations exactly for capital-and-interest mortgages. What it cannot include are lender fees, the exact day interest is charged, and any rate changes during the term. Treat it as a precise estimate of the core payment, not the final offer figure.