Mortgage calculator
Every bank's calculator asks for your gross salary, applies a multiple, and hands back a borrowing limit. Nobody pays a mortgage out of gross pay. This one works out the payment and then shows it against the money that actually reaches your account, along with the LTV band you are being priced in and the purchase tax where you are buying.
20.0% of the price
£240,000 over 30 years at 4.65%
£1,237.53 a month
That is 41% of your £2,993.30 monthly take-home, leaving £1,755.77 for everything else.
Your loan-to-value is 80.0%
Lenders price in bands, not on a sliding scale, so you are being quoted the 80% LTV rate. Another £15,000 of deposit would reach the 75% band and a better rate. Anything less than that changes nothing at all — which is why part of a deposit can be worth keeping back rather than rounding up.
£60,000 more would reach 60%, past which extra deposit stops improving the rate.
This loan is 5.3× your salary. Most lenders cap around 4.5×, though it is affordability rather than the multiple alone that decides an application.
What it costs to buy
| Property price | £300,000 |
| Deposit | £60,000 |
| Mortgage | £240,000 |
| Stamp duty (first-time buyer) | £0.00 |
| Cash needed on completion | £60,000.00 |
| Total interest over 30 years | £205,510.20 |
No stamp duty up to £300,000 and 5% from £300,001 to £500,000. Over £500,000 the relief is lost entirely, not tapered. Legal fees, a survey and moving costs typically add £2,000–£4,000 on top and are not included here. Stamp Duty Land Tax rates checked 2026-09-01 against HMRC. Your take-home is calculated with the standard 1257L code and no pension or student loan — adjust those on the main calculator if they apply, since both change what you can actually service.
Why a bigger deposit sometimes buys you nothing
Lenders do not price on a sliding scale. They price in bands — typically 95%, 90%, 85%, 80%, 75% and 60% loan-to-value — and your rate is set by whichever band you land in. Going from 78% to 76% changes nothing. Going from 76% to 75% can change the rate on the whole loan. So the only deposit increases that pay for themselves are the ones that cross a boundary, and the sensible move is to work out where the next boundary is before deciding how much to put down.
The band that surprises people is the last one. 60% is normally the floor: below it lenders generally stop offering better pricing, so a 65% deposit and a 50% deposit are quoted much the same rate. Every pound past that point is capital locked into a house instead of sitting in reserve, and it buys no discount at all. That is worth knowing before emptying an ISA into a deposit.
Three different purchase taxes, not one
There is no single UK stamp duty. England and Northern Ireland charge Stamp Duty Land Tax, Scotland charges Land and Buildings Transaction Tax and Wales charges Land Transaction Tax. The thresholds differ, the rates differ, and so does first-time buyer treatment: England gives relief up to £500,000, Scotland lifts the nil-rate band by £30,000 instead, and Wales offers no relief at all because its £225,000 nil-rate band already applies to everyone. The calculator switches tax with the country you pick, so the figure is the one you would actually pay.
One trap worth naming: in England the first-time buyer relief is a cliff, not a taper. At £500,000 you pay £10,000. At £500,001 the relief vanishes entirely and the standard scale applies to the whole price, so a single extra pound of purchase price costs about £5,000 in tax. If you are negotiating near that line, it is worth knowing which side of it you want to be on.
What share of take-home is too much?
There is no official limit, and lenders test affordability rather than applying a ratio. As a rough shape, under 30% of take-home is comfortable, 30–40% is manageable but leaves less room for a rate rise at renewal, and above 40% means the rest of your spending is being organised around the mortgage. What matters more than the percentage is what happens when you refix: run the payment again at two or three points higher and see whether the number still works. That, rather than the current rate, is the risk you are actually taking on.
Bear in mind this calculator assumes the standard 1257L tax code with no pension contribution or student loan. Both reduce take-home, and a student loan in particular takes 9% of everything above its threshold, so if either applies to you the honest share is higher than the figure above. Work out your real net pay on the main calculator first, or check the student loan calculator if you are on one of the five plans.
2026/27 income tax rates, checked 2026-08-28 by Hadi. Purchase tax rates checked 2026-09-01 against HMRC, Revenue Scotland and the Welsh Revenue Authority. This is an estimate, not mortgage advice: rates you are offered depend on the lender, your credit file and their affordability assessment. Method on the about page.