BMI Calculator

Body mass index in metric or imperial, with your WHO category and healthy range.

Stays on your device. This tool runs in your browser — nothing you paste or open ever leaves it. Nothing uploaded, nothing to leak.

Units

Height

Weight

Height

ftin

Weight

BMI is a general screening figure, not a diagnosis — talk to a health professional about your own health.

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How to use it

Choose metric or imperial, enter your height and weight, and your BMI, category and healthy-weight range appear instantly. Switching units keeps your figures.

BMI Calculator — TechWhack Score

9.5/10

Privacy 10/10

Your height and weight are used in the browser only — nothing is sent to a server or saved.
Speed 10/10

Your BMI, category and healthy range update as you type.
Features 8/10

Works in metric or imperial, shows your WHO weight category, and the healthy-weight range for your height — with a clear note on BMI’s limits.
Free 10/10

No sign-up, no limits.

Verdict: Gives the number and the context — your category and the weight range for your height — while being upfront that BMI is a screening figure, not a diagnosis.

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A BMI calculator works out your body mass index from your height and weight — BMI = weight (kg) ÷ height (m)², or 703 × pounds ÷ inches² in imperial. It shows your number, your WHO category (underweight, normal, overweight or obese) and the healthy-weight range for your height. BMI is a general screening figure, not a medical diagnosis.

What your BMI means

On the standard WHO scale, under 18.5 is underweight, 18.5–24.9 is a normal (healthy) weight, 25–29.9 is overweight, and 30 or over is obese. The tool also shows the weight range that would put you in the healthy band for your height.

What BMI can’t tell you

BMI is a quick screening number, not a diagnosis. It doesn’t separate muscle from fat, so very muscular people can read high, and it isn’t designed for children, pregnancy, or some ethnic groups where the thresholds differ. Use it as a rough guide and talk to a doctor or another qualified health professional about your own health — this tool does not give medical advice.

FAQ

How do I calculate BMI?Divide your weight in kilograms by your height in metres squared (kg ÷ m²). In imperial, multiply pounds by 703 and divide by height in inches squared. This tool does both automatically.

What is a healthy BMI?A BMI of 18.5 to 24.9 is classed as a normal, healthy weight on the WHO scale. The calculator shows the exact weight range for your height.

What are the BMI categories?Under 18.5 is underweight, 18.5–24.9 normal, 25–29.9 overweight, and 30 and above obese.

Is BMI accurate for everyone?No — it is a general screening tool. It doesn’t distinguish muscle from fat and isn’t designed for children, pregnancy or some populations, so treat it as a guide, not a diagnosis.

Is my height and weight stored?No — the calculation runs in your browser and nothing is uploaded or saved.