Work out what you can hold onto.
Most calculators stop at the offer. This one carries on: what a house at a given price leaves you each month once the payment goes out, which of three limits ran out first, and whether those figures still stand when your fixed rate ends or one income drops.
Work it outFive steps, a couple of minutes. No account, no email, nothing sent anywhere — the arithmetic runs in this browser.
Know which limit you hit
Your deposit, what a lender will lend, what you can pay each month — whichever runs out first is the only one worth working on, and each needs a different thing done about it. So you always get told which one it was, not just a number.
Your saving stays yours
Calculators that treat saving as spare money always decide the house is affordable, because there is always something left once you stop saving. Here it is money you are keeping, and the answer is what the house leaves standing next to it.
See what happens when your fix ends
Two or five years in, your fixed rate runs out and you take a new one — at whatever rates are by then. See what the same loan costs on a new deal at a higher rate, in the same size type as the headline, because that is the payment you live with longest.
See the room you have
How far your salary — and any partner's — could fall before you are in trouble, and how long your savings would last if one income stopped altogether. That is the difference between a house that works and one that works only while nothing changes.
Worked examples
The same three households, priced under each of the UK's three purchase-tax rules. Every figure is worked out by the model rather than typed into the text. Sign up to open one — the calculator itself needs no account.
Nothing here is advice and nothing is a recommendation. It describes what follows from figures you enter, with the whole working shown, so you can check every step of it yourself.
Read how the model works