About the UK Calculator Platform
The UK Calculator Platform is a free collection of 253 calculators, operated by Jomovate. It exists to answer a specific kind of question well: the everyday numerical question a person in the UK actually has, worked out using UK rules, with the reasoning shown rather than hidden.
UK-first, not UK-flavoured
Most calculators on the open web are built for a different tax system and relabelled. This one is not. Income Tax, National Insurance, student loan repayments, Stamp Duty and its Scottish and Welsh equivalents, ISA and pension allowances, and Child Benefit are modelled against UK legislation and HMRC guidance, and the tax year the figures belong to is stated on the page rather than assumed.
Where a rule genuinely differs across the UK nations, that difference is modelled rather than averaged away. Of the 253 published calculators, 51 depend on rules that can change when legislation changes; the remaining 202 are general mathematical, scientific or everyday tools whose method does not move with a Budget.
What the platform covers
The calculators span UK tax and salary, mortgages and property, pensions and retirement, investing and wealth, ISAs and tax wrappers, business and commercial finance, health and fitness, conversions, maths, geometry, statistics, science, dates, motoring, home construction, technology and everyday life. Each one sits in a category so that related tools are easy to find from any starting point.
How the calculators are built
Three things sit behind every result, and they are deliberately kept apart from one another.
- A calculation engine. The arithmetic lives in deterministic code, separate from the page that displays it. The same inputs always produce the same outputs, and the engine can be run and checked without a browser involved.
- Versioned UK rules. Rates, thresholds and bands are held as data tied to a named tax year, rather than being scattered through the code as loose numbers. That is what makes an annual rollover a reviewable change instead of an archaeology exercise.
- Editorial content. Where a calculator has a published guide, the method, worked example, assumptions, limitations and official sources are authored as structured data. A worked example carries the exact inputs that produced it, so the automated suite re-runs the engine and fails if a published figure no longer matches the arithmetic it claims to explain.
Automated verification runs across all three. There are reference benchmark cases with independently derived expected values, unit tests, browser-level regression checks and automated accessibility scans. How we check our figures sets out that process in full, including what it does and does not prove.
Why we show the method
A number on its own is not much use. If you cannot see which rules were applied, what was assumed, and where the figures came from, you have no way to judge whether the answer fits your situation — or to spot when it does not.
So the platform publishes the governing formula, a worked example, the assumptions built into the model, the limitations of that model, and links to the official sources behind rule-sensitive figures. Our editorial policy sets out the standards that content is held to, including the hierarchy of sources that statutory figures must be evidenced against.
What these calculators are not
The platform is an educational and informational resource. It is not regulated, it does not provide financial, tax, legal or medical advice, and it makes no personal recommendations.
Every calculator simplifies. Real legislation is full of interactions, reliefs, elections and edge cases that a general-purpose tool cannot reasonably capture, and real circumstances are frequently more complicated than any set of input fields. A calculator here will tell you what its stated model produces for the figures you entered. It cannot know about your other income, your particular scheme rules, a relief you are eligible for, or a change in the law that has not yet been reflected here.
Where a decision carries real financial, legal or health consequences, treat a result from this platform as a starting point for a better question, and check it with someone qualified to advise on your circumstances — an accountant, an FCA-regulated adviser, a solicitor or conveyancer, or a medical professional as appropriate. The disclaimer sets out the limits in full.
Corrections
If a figure looks wrong, we want to know, and a specific report is far more useful than a general impression. The contact page explains what to include so that a suspected error can be reproduced and checked quickly, and updates records the corrections and changes that have already been made.