About Mortgages Calculators UK
We build free, accurate mortgage calculators for the UK market. No sign-ups, no lead forms, no selling your details to brokers. Just tools that do the arithmetic properly and guides that explain what the numbers mean.
Why this site exists
Most UK mortgage calculators are lead-generation forms wearing a calculator costume. You enter your details, get a rough number, and shortly afterwards receive calls from three brokers who paid for your data. The calculation itself is often simplified to the point of being misleading, with no fee handling, no overpayments, no distinction between the three UK property taxes.
We wanted the opposite: tools that give you the complete answer, immediately, without asking for anything. Every calculation on this site runs entirely in your browser. Nothing you type is sent anywhere, stored, or seen by us.
How we build the calculators
- Published formulas only. Repayment mortgages use the standard annuity formula. Interest-only uses simple monthly interest. Stamp duty uses genuine band-by-band marginal calculation, including the one case (Scotland's Additional Dwelling Supplement) where the tax is charged on the full price instead.
- Reconciled against primary sources. Stamp duty outputs are checked against HMRC, Revenue Scotland and the Welsh Revenue Authority tools. Repayment figures are checked against lender illustrations.
- Dated data. Every page carries the date its data was last verified. If a figure is more than a few months old, you can see that rather than having to guess.
- Assumptions stated. Where a calculator makes an assumption, such as a stress rate, a void allowance or a growth rate, it says so on the page and lets you change it.
Where our data comes from
| Data | Source | Update cadence |
|---|---|---|
| Base rate | Bank of England Monetary Policy Committee | Eight times a year |
| Average mortgage rates | Rightmove weekly tracker, Moneyfacts averages | Weekly |
| SDLT rates | HM Revenue & Customs | After each Budget |
| LBTT rates | Revenue Scotland | After each Scottish Budget |
| LTT rates | Welsh Revenue Authority | After each Welsh Budget |
| House prices | ONS UK House Price Index, Nationwide, Lloyds | Monthly |
| Lending rules | Bank of England FPC, FCA MCOB, lender criteria | As changes are announced |
What we are not
We are not a mortgage broker and we are not authorised by the Financial Conduct Authority to give mortgage advice. Nothing on this site is a personal recommendation, a mortgage offer, or advice about your situation.
What we provide is information and calculation. That is genuinely useful for working out what you can afford, comparing options and understanding what a lender will look at, but the decision itself should involve a qualified adviser or the lender directly.
How we make money
Through advertising and, in future, clearly-labelled affiliate links to comparison services. We do not sell, share or transmit anything you enter into a calculator, because it never leaves your browser in the first place. We do not run lead-generation forms. If we ever add an affiliate link, it will be labelled as one, and it will not change what a calculator tells you.
Corrections
If you find an error in a rate, a tax band, a formula or a fact, please tell us. We would rather be corrected than be wrong, and we update the “verified” date on any page we change. Get in touch.