For most sedentary adults it's a reasonable proxy for body fat. For athletes, very tall or short people, or anyone with unusual body composition, a body-fat measurement or waist-to-height ratio is more informative.

Do age and sex matter?

The WHO BMI thresholds are the same for adult men and women. Some regional guidelines (e.g. Asian populations) use lower thresholds for overweight and obese categories.

Is the BMI calculator free?

Yes — free to use, with no signup, no limits and no personal details required. The site is supported by advertising rather than subscriptions.

Is my data saved or sent anywhere?

No. Every calculation runs in your browser, so the numbers you type are never transmitted to us or stored on a server. Closing the tab discards them.

Can I rely on this instead of seeing a professional?

No. These formulas give a useful reference point, but they cannot account for your medical history or body composition. Use the result to inform a conversation with a qualified professional, not to replace one.

Can I share or save my results?

Yes. Your inputs are stored in the page URL, so you can copy the link from the address bar (or use the share button) to bookmark a scenario or send it to someone else.

BMI Calculator

Body Mass Index in metric or imperial units, with WHO category and your healthy weight range.

Your details

Height

Weight

Your BMI

24.5

Healthy weight

Category range

<18.518.5–2525–3030+

Healthy weight range for your height

56.7 – 76.3 kg

How this is calculated

BMI is weight in kilograms divided by height in metres squared: BMI = kg ÷ m². The WHO categories are: underweight (<18.5), healthy (18.5–24.9), overweight (25–29.9), and obese (≥30).

BMI is a rough screening tool. It doesn't distinguish muscle from fat, so athletes often score as "overweight" despite being lean. It's also less reliable at the extremes of height and for children, pregnant women, and older adults.

Who this calculator is for

This is aimed at people tracking their own health who want a clear number to work from rather than a vague guideline. It is useful as a starting reference point when setting goals or reviewing progress, and as context for a conversation with a qualified professional.

Assumptions and accuracy

These are population-level formulas. They do not account for body composition, muscle mass, pregnancy, medical conditions, or medication, so an individual result can be some way off. This is general information, not medical advice — speak to a doctor or registered dietitian before acting on it.

Frequently asked questions

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