NHS Calculator
Quick Calculator
Use the keypad or your keyboard: digits, plus, minus, multiply, divide, percentage, brackets, Enter to calculate, Backspace to delete, Escape to clear.
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NHS Calculator brings together practical, NHS-referenced health calculators for the United Kingdom — from BMI and calories to pregnancy dates, heart risk and everyday health tools. Everything is free to use, works on your phone, and is built around the UK measurement units you use at home.
Every calculator explains what it measures, how to use it and how to interpret the result. Clinical calculators are published only after their formula, thresholds and sources have been verified against authoritative UK guidance.
Popular NHS Calculators
All Calculators
Weight & Body6
Pregnancy & Child10
Calories & Nutrition9
Heart & Health Risk6
Clinical Tools11
Everyday Health6
NHS Tools & Eligibility8
Converters & Other Tools2
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How Our Calculators Work
Each calculator follows a standard, transparent process. We start from the published NHS or UK clinical method for that measure — including its formula, thresholds and units — then build a simple tool that asks only for the inputs that method needs. Results are calculated in your browser, so your figures never leave your device.
Before any clinical calculator is published it is checked against the original source: exact formula, version of the guidance, units, interpretation bands and known limitations. Only then does the calculator move from draft to a live page.
Accuracy, Sources and Limitations
Our calculators use methods from published NHS pages, UK clinical guidelines (such as NICE) and peer-reviewed research, and each page lists its specific sources with the version and review date. Accuracy depends entirely on the figures you enter, so always double-check your measurements.
All results are estimates for general information. They are not a diagnosis, do not replace professional advice, and some tools are intended as screening aids rather than clinical measurements. Where a method has known limitations — for example in certain age or health groups — we state them on the page.
Independent Website Notice
NHS Calculator is an independent website and is not affiliated with, endorsed by or connected to the National Health Service. The name is used descriptively to show that our tools reference publicly available NHS and UK health guidance.
Frequently Asked Questions
Is this website affiliated with the NHS?
No. NHS Calculator is an independent website and is not affiliated with or endorsed by the NHS. The name is used descriptively because the calculators reference publicly available NHS guidance and UK health standards.
How do I use the calculators?
Enter the requested figures into the relevant calculator and press calculate. Results are shown immediately. Every calculator explains what it measures, how to use it, how to interpret the result and its limitations before it is published.
Are calculator results medical advice?
No. Results are estimates for general information only and never replace advice from a qualified health professional. If you are concerned about your health, contact your GP or NHS 111 in the UK, or call 999 in an emergency.
Why are some calculators in draft?
A calculator is published only after its formula, thresholds, units, source version and limitations have been checked against authoritative UK references. Unverified calculators remain unpublished drafts and are not shown to visitors.
Where do the calculators' methods come from?
Methods are based on published NHS and UK clinical guidance and peer-reviewed sources, referenced on each page. Every page lists its authoritative sources and its last review date.