About FinToolbox
FinToolbox is a set of free UK financial calculators. There are no logins, no subscriptions and no intrusive tracking. Every calculation runs in your browser, so the numbers you type never reach our servers.
Who operates FinToolbox
FinToolbox is a trading name of Axiom Testing Ltd, a private limited company registered in England and Wales under company number 17267026. Our registered office is in Redhill, United Kingdom. Axiom Testing Ltd is a UK software QA consultancy — the same people who test other companies' software build and check these calculators. You can read more about the company at axiomtesting.co.uk.
You can reach us at contact@fintoolbox.co.uk or through our contact page. If you spot a figure that looks wrong, please tell us — we would rather hear about it than have someone rely on it.
Where our figures come from
Every rate, threshold and allowance on this site comes from published GOV.UK and HMRC guidance. We do not estimate rates or carry them over from one year to the next without checking.
12 of our calculators depend on statutory rates that change. Each of those pages lists the exact GOV.UK pages its figures come from, so you can verify any number yourself in one click. The rest are based on standard formulas — compound interest, ROI, break-even — which do not change from year to year.
Our current figures cover the 2026/27 tax year and were last checked against GOV.UK on . We re-check them at the start of each UK tax year in April, and whenever a Budget or Autumn Statement changes something mid-year.
To be clear about what we are: FinToolbox is built by software engineers, not accountants. Our calculators are not reviewed by a qualified tax adviser. We are careful about sourcing and we show you our workings, but these tools give estimates for information only — they are not financial or tax advice. For anything that carries real consequences, speak to a qualified professional. See our disclaimer for the full position.
What We Offer
Our calculators span seven categories covering the financial questions that matter most:
- VAT calculators — standard VAT, reverse VAT, flat-rate scheme, import VAT, and more
- Tax calculators — income tax, capital gains, dividend tax, national insurance, and self-assessment
- Business calculators — profit margins, break-even, cash flow, payroll, startup valuation, and more
- Property calculators — stamp duty, mortgage repayments, buy-to-let yield, and remortgage savings
- Marketing calculators — ROI, ROAS, customer acquisition cost, conversion rate, and churn
- Savings calculators — emergency fund planning and debt payoff strategies
- Investment calculators — portfolio growth projections and risk/return analysis
All calculators run entirely in your browser — no data is sent to our servers.
Our Philosophy
We believe financial tools should be:
- Fast — instant results with no page reloads
- Accurate — figures based on current UK rates and rules
- Easy to use — clean inputs, clear outputs, no jargon
- Accessible — works on any device, including screen readers
- Free — no paywalls, no sign-ups
- Private — all calculations happen locally in your browser
Contact
Have a suggestion, spotted an error, or want to get in touch? Visit our Contact page.