5 tools
Health calculators
Estimate common body measures and see what the numbers do and don't tell you.
BMI, calorie needs, body fat, ideal weight and waist-to-height ratio, with healthy ranges and the limits of each measure explained.
- ✓ Ranges from WHO, NHS, CDC and NICE guidance
- ✓ The limits of each measure explained
- ✓ Not a substitute for advice from a doctor
BMI Calculator
Know your Body Mass Index in seconds — with healthy-range context.
Open calculatorCalorie Calculator
Daily calories to maintain, lose or gain weight — BMR and TDEE using Mifflin–St Jeor.
Open calculatorBody Fat Calculator
Estimate body fat percentage with a tape measure — the U.S. Navy circumference method.
Open calculatorIdeal Weight Calculator
Healthy weight range for your height, plus the Devine, Robinson, Miller and Hamwi formulas.
Open calculatorWaist-to-Height Ratio Calculator
Keep your waist to less than half your height — check your ratio against NICE bands.
Open calculatorHow to get the most from health tools
Each health calculator has the same layout: the calculator at the top, then the formula, a worked example, common uses, tips, mistakes to avoid and the sources we used. Run your own numbers first, then use the related calculators at the bottom of the page to check from another angle, such as GST alongside Discount, or Age alongside Date Difference.
Calculations run in your browser, so the numbers you enter are not sent anywhere. If a figure is going into a contract, tax return or medical record, check it against the official source linked on the calculator page.
Common questions
Other categories
Percentage Calculator
What is X% of Y? What % is X of Y? Answered with steps.
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Percentage Increase / Decrease Calculator
Old → new percent change, with increase vs decrease explained.
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Age Calculator
Exact age in years, months, days — plus totals and next birthday.
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