UK Mortgage Calculators: Borrowing, Repayments, Stamp Duty and LTV

The quick calculator below turns a property price, deposit, rate and term into a monthly payment, a loan-to-value band and the total interest over the term, in one pass. Six full calculators then take each of those figures further: remortgage saving, borrowing range, repayments, stamp duty, buy-to-let rental cover and the LTV band itself. Mortgage One is a whole of market mortgage adviser that checks calculator estimates against live lender criteria for buyers, remortgagers and landlords.

If the monthly figure the calculator returns is higher than the payment you had in mind, call 01202 155992 or contact Mortgage One.

How does the quick calculator work out your monthly payment?

It applies the standard repayment formula: the loan is the price minus the deposit, interest is charged monthly at one twelfth of the annual rate, and the payment is set so the balance reaches zero at the end of the term. A £200,000 loan at 5% over 25 years costs £1,169 a month and about £150,800 in interest.

Switch the basis to interest-only and the payment drops to the interest alone, £833 a month on the same loan, with the full £200,000 still owed at the end of the term. The loan-to-value figure is the loan divided by the price, and the band label tells you which pricing tier a lender would place you in, because lenders price in steps at 60%, 75%, 80%, 85%, 90% and 95% rather than on a sliding scale. A simple mortgage calculator like this one is the right first step, and for most people it is all the arithmetic needed before a viewing.

What it leaves out matters as much as what it includes. Lenders calculate interest daily rather than monthly, so a lender illustration will differ from this figure by a few pounds. A product fee added to the loan attracts interest for the whole term. A monthly mortgage calculator is only as good as the rate you give it, and that rate is an assumption until a lender has priced your case, so run the figure at the rate you have been quoted, then again one percentage point higher, to see what a rate move does to the monthly cost. The full repayment calculator in the grid below goes further on term and repayment basis comparisons.

Which of the six full calculators answers your question?

Match the tool to the decision. A deal ending in the next six months needs the remortgage calculator. A purchase runs borrowing range, then stamp duty, then repayment. A rental needs the buy-to-let stress test. Anyone within a few per cent of a loan-to-value boundary needs the LTV calculator before any rate comparison. The cards below open each one.

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Run them in the order a broker would rather than one at a time. On a purchase, the borrowing range sets the ceiling, stamp duty is the largest single upfront cost after the deposit and is charged in slices with a surcharge on additional property, and the repayment figure is the number that has to fit the monthly budget. A borrowing range with no loan-to-value check tells you what a lender might advance but nothing about the rate band you would land in.

On a remortgage the order reverses. Most lenders let you secure a new deal up to six months before the current one ends, so the saving and break-even month come first, and the LTV figure then decides which rates are open to you, because capital repaid and any price growth can drop you a band without a penny of new deposit. Our remortgaging guide covers the product transfer alternative and the timing in full. On a rental, the stress test sizes the loan before the rate does, and the buy-to-let mortgage guide sets out how coverage ratios differ by tax status and ownership structure.

Why the calculator figure and the lender's figure differ

A calculator applies one set of assumptions. A lender applies its own: a stress rate at least one percentage point above the pay rate for five years unless the fix runs five years or more, its own treatment of bonus, overtime and self-employed income, and its credit and property rules. Identical salaries produce offers tens of thousands of pounds apart.

The gap sits mostly in income treatment. One lender takes 100% of a contractual bonus, another averages three years, another caps it. Overtime may need six months of evidence at one lender and twelve at the next. Self-employed applicants can be assessed on the latest year, a two-year average or salary plus dividends, and the answer moves the loan by a wide margin. Foreign currency income narrows the panel again, often with a haircut on the converted figure. Our guide to income multiples sets out which lenders stretch furthest and what they ask for in return, and the mortgage affordability guide explains how the stress test and the expenditure model cut the headline multiple down.

Property is assessed as well as the borrower. Flats above commercial premises, short leases, high-rise ex-local authority blocks and non-standard construction all shrink the lender pool or cap the loan-to-value, however strong the affordability looks. On a buy-to-let, most lending is geared to a maximum of 75% loan-to-value, and the coverage ratio a lender applies depends on your tax status and ownership structure. The full picture of what lenders assess is in our guide to understanding mortgage criteria.

To have your income, deposit and property tested against live lender criteria rather than one set of assumptions, call 01202 155992 or contact Mortgage One.

What every calculator on this page assumes

Capital repayment unless the tool offers interest-only, interest applied monthly, fees paid up front rather than added to the loan, a single set of assumptions for every applicant, and England and Northern Ireland thresholds on stamp duty. The figures are planning estimates, not lending decisions, and where a tool carries a market rate the check date sits on that page.

Fees added to the loan cost more than fees paid, because interest is charged on them for the whole term. Scotland and Wales run their own property taxes, Land and Buildings Transaction Tax and Land Transaction Tax, with different bands and different additional property supplements, so a purchase there takes its figure from the Revenue Scotland or Welsh Revenue Authority calculator rather than the SDLT tables. Where a tool carries market rates, our rate forecast carries the base rate and the next decision date if you want to test a higher or lower rate than today's.

The one assumption to change deliberately is the rate. A rate quoted today is the rate for the initial deal, not for the whole term, so run the monthly figure a second time at the rate you would revert to when that deal ends. The difference between the two is the cost of doing nothing at the end of a fixed period, and it is usually the most persuasive number on this page.

When to stop calculating and speak to a broker

Stop when the calculator's answer is not the answer you need. A borrowing range that falls short of the price, a rental that fails the stress test, an LTV just over a band boundary, or income that is anything but a straightforward salary are criteria problems. The fix is matching the case to a lender, not repeating the arithmetic.

A calculator result and a lender decision that have already diverged almost always differ on a criteria point, not the maths. The same applies before an application: the top of a borrowing range is a lender-specific outcome that needs the right lender, and applying to the wrong one adds a hard credit search to your file for nothing. Our guide to using a mortgage broker sets out what a whole of market search changes at each of those points.

Residency, income currency and contract type narrow the panel further for anyone working abroad, and mainstream calculators model none of it. Our expat mortgage and seafarer mortgage pages cover how lenders treat those cases before the numbers are run.

For a free initial consultation that turns the figure on this page into a lender-specific borrowing position, call 01202 155992 or contact Mortgage One.

The information provided in this article is for general guidance only and does not constitute personal or regulated financial advice. If you'd like to understand what these moves could mean for you, speak to Mortgage One. We can explain your options and timings based on your specific circumstances.

FAQs

1. Which mortgage calculator should I use first?

The one that matches the decision in front of you. If a deal is ending, the remortgage calculator. If you are buying, the borrowing range, then stamp duty, then repayment. If you are letting, the buy-to-let stress test. Run the LTV calculator alongside whichever you start with, because the band you land in decides which rates you are quoted.

2. Can I get a £200,000 mortgage on a £40,000 salary?

That is five times income, above the 4 to 4.5 times most lenders start from, which puts the usual ceiling nearer £160,000 to £180,000. A smaller group of lenders lend at 5 to 5.5 times income for applicants who meet their conditions on deposit, credit profile or profession, so it is possible with the right lender and low outgoings, but it is not the default outcome.

3. How much interest will I pay on my mortgage?

It depends on the loan, the rate and the term, and the term does more damage than most people expect. A £200,000 repayment mortgage at 5% over 25 years costs about £150,800 in interest. Over 35 years the monthly payment falls by around £160, but total interest rises to roughly £223,900. The quick calculator above shows the figure for your own numbers.

4. Are mortgage calculator results accurate?

They are reliable arithmetic on the inputs you give them and nothing more. The final figure depends on the lender's affordability model, how it treats your income, your credit profile, the property, fees and the documents you can evidence. Two lenders assessing the same case regularly produce different maximum loans, and lenders charge interest daily where calculators work monthly.

5. Can a 46-year-old get a 25-year mortgage?

Usually, yes. A 25-year term from 46 ends at 71, inside the maximum age most mainstream lenders set at the end of the term, commonly 75 to 80 on a repayment basis, and some building societies set no upper limit at all. Where the term runs past your anticipated retirement age, the lender will want evidence of the income that will pay the mortgage after you stop working.

6. Is a mortgage in principle calculator the same as a decision in principle?

No. A mortgage in principle calculator is an affordability estimate built on income multiples and outgoings. A decision in principle is a lender's own indication, usually after a credit search, and it still sits below a formal offer, which follows full underwriting and a valuation. Our mortgage in principle guide covers the process in full.

7. When is it worth speaking to a broker rather than running another calculation?

Once you have a figure and a question the figure does not answer. Whether a lender will accept your bonus, whether the rent clears its stress test, whether a valuation will hold the LTV band, or whether anyone lends on your income type are criteria questions, and they are answered by matching the case to a lender rather than by re-running the numbers.