Free Health Calculators and Tools
Practical calculators with the method, assumptions and limits explained on every page. Everything runs in your browser.
Private by design: nothing you enter is sent or stored.
BMI Calculator
Calculate your adult body mass index in metric or imperial units, see the category and the healthy weight range for your height.
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Daily Water Intake Guide
See official reference values for how much water adults need each day, how much comes from drinks, and when you may need more.
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Sleep Calculator
Find bedtimes that fit your wake-up time, or wake-up times if you go to bed now, based on 90-minute sleep cycles.
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Age Calculator
Work out an exact age in years, months and days, total days lived, and days until the next birthday.
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Health Unit Converter
Convert weight, height, temperature, fluids, food energy, blood glucose (mmol/L ↔ mg/dL) and HbA1c (% ↔ mmol/mol).
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Calorie Needs Estimator
Estimate resting and daily maintenance energy needs with the Mifflin–St Jeor equation, with the method and its limits explained.
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