About CalcBritain
Free, accurate UK financial calculators. No sign-up. No ads. No faff.
What is CalcBritain?
CalcBritain is a free, independent set of UK tax and financial calculators. We built it because too many salary and tax tools are cluttered with ads, require you to create an account, or return results you can't trust. We wanted something clean, fast, and accurate.
Everything runs in your browser. There is no sign-up and no account — the figures you enter never leave your device. Analytics are optional and stay off unless you accept the cookie banner. Just enter your figures and get your answer.
What calculators do we offer?
We have 200+ UK calculators. Some of the most popular:
- Take-home pay — income tax, National Insurance, pension deductions, and student loan repayments for all four UK nations (England, Scotland, Wales, Northern Ireland).
- Mortgage affordability — how much you might be able to borrow based on income and outgoings.
- Mortgage repayment — monthly repayments and total cost over the mortgage term.
- Stamp Duty — Stamp Duty Land Tax (England & NI), Land and Buildings Transaction Tax (Scotland), and Land Transaction Tax (Wales).
- Pension — tax relief on contributions and projected pension pot growth.
- Savings — compound interest and ISA allowance projections.
…plus 200+ more across tax, property, savings, motoring, pensions, health and everyday life — see them all on the calculators page. We add new ones regularly, and each is verified against authoritative sources before it goes live.
Where do the figures come from?
Every rate, threshold, and rule used in our calculators is sourced directly from the relevant government authority and updated at the start of each tax year:
- England and Northern Ireland income tax and National Insurance: HMRC (gov.uk)
- Scotland income tax (Scottish Rate of Income Tax — SRIT): Revenue Scotland
- Wales — Land Transaction Tax: Welsh Revenue Authority (WRA)
- Stamp Duty Land Tax (England & NI), pension relief rules, ISA limits: gov.uk
Tax-year-specific calculators are set to the 2026/27 tax year by default, with 2025/26 available as an option where it applies.
Methodology and accuracy
Our calculation engine is written in TypeScript and runs entirely in your browser. Every calculator ships with a suite of “golden tests” — expected output values traced directly to authoritative HMRC or government publications. Our continuous integration pipeline fails if any of these golden values deviate by even a penny. This means we catch any regression in accuracy automatically before it reaches you.
We handle the following correctly:
- Scottish income tax bands (SRIT) diverging from UK-wide bands
- Wales Land Transaction Tax (different from Stamp Duty Land Tax)
- Personal allowance taper (income over £100,000)
- All student loan repayment plans (Plans 1, 2, 4, 5, and Postgraduate)
- Pension contributions via salary sacrifice, relief at source, and net pay arrangements
- Blind Person's Allowance
- First-time buyer reliefs and additional-dwelling surcharges for stamp duty
Despite this care, our figures are always estimates — your individual tax position depends on your full financial picture. Always verify with HMRC or a qualified adviser before making decisions. See our Terms of Use for more.
Privacy by design
The figures you enter never leave your browser. All calculations are client-side JavaScript — nothing is sent to our servers. For aggregate usage we use Google Analytics, but only if you accept the cookie banner — analytics are denied by default. No advertising. No ad trackers. Read our Privacy Policy for the full picture.
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Get in touch
Found an error? Have a suggestion? Or just want to say thanks? We'd love to hear from you — contact us.