Calculators
BMI Calculator
Calculate body mass index from height and weight in metric or imperial units, its adult category and the weight range for a healthy BMI.
- Runs in your browser
- Nothing uploaded
The tool
Enter your numbers below. Results update as you type, and nothing leaves your browser.
Everything you enter stays on your own machine. Nothing is sent to us or to anyone else, which you can confirm in your browser network tab.
What people use it for
- Quick weight status screening
- Tracking changes over time
- Health and fitness education
- Pre-assessment for fitness programmes
About this tool
What the BMI Calculator does
Body mass index (BMI) is weight in kilograms divided by height in metres squared. For adults, the World Health Organization categories are underweight below 18.5, healthy 18.5 to 24.9, overweight 25 to 29.9 and obese 30 or above. BMI is a screening measure: it does not distinguish muscle from fat.
It also works as a BMI and body fat calculator or a body mass index calculator.
Formula
- BMI = weight (kg) ÷ height (m)²
- Imperial: BMI = 703 × weight (lb) ÷ height (in)²
Worked example
Using the starting values in the calculator above:
| Input | Value |
|---|---|
| Units | Metric (kg, cm) |
| Weight | 72 |
| Height | 175 |
| Result | Value |
|---|---|
| BMI | 23.5 |
| Adult category | Healthy weight |
| Weight range for a BMI of 18.5–24.9 | 57 to 76 kg |
How to read the result
BMI can overestimate fat in muscular people and underestimate it in older adults; waist measurement adds useful context.
Children and teenagers use BMI-for-age percentiles rather than adult categories.
General information, not medical advice. Speak to a qualified health professional before making changes to diet, exercise or treatment.
Related calculators
- Body Fat Calculator: Estimate body fat percentage with the US Navy circumference method from height, neck, waist and hip measurements.
- Calorie Needs Calculator: Calculate basal metabolic rate with the Mifflin-St Jeor equation and total daily energy expenditure for your activity level.
- Calorie Deficit Calculator: Calculate the daily calorie target and estimated time to reach a goal weight from maintenance calories and a weekly loss rate.
- Calories Burned Calculator: Estimate calories burned during exercise and daily activities from body weight, duration and the activity’s MET value.
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Questions
Questions about this tool
The things clients actually want to know — costs, timelines, ownership and what happens after launch.
Divide weight in kilograms by height in metres squared.
For most adults, 18.5 to 24.9. Some populations use lower cut-offs for health risk.
It is a useful screening tool but does not measure body fat directly.
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