BMI calculator
Calculate your BMI in kg and cm or pounds and feet, with its WHO category and the weight range that corresponds to a healthy BMI for your height.
- Free
- No sign-up
- No file uploaded
- Windows, Mac, Android, iPhone
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About this tool
Enter your weight and height: your body mass index appears with its World Health Organization category and the weight range that gives a healthy BMI for your height.
When to use it
Checking where you stand
BMI is the measure doctors use to quickly place an adult between underweight, healthy weight, overweight and obesity.
Setting a realistic goal
The healthy weight range gives an interval, not a single number: a target you can actually reach.
Metric or imperial
Know your weight in pounds and your height in feet? The calculator handles both systems and converts your values.
How to use
- Choose your units.
- Enter your weight and height.
- Read your BMI and its category.
How it works
BMI is weight in kilograms divided by height in meters squared. For 70 kg and 1.75 m: 70 / (1.75 × 1.75) = 22.9. In imperial units the values are converted first.
The WHO cut-offs for adults are 18.5 (below: underweight), 25 (overweight), 30, 35 and 40 (obesity classes I, II and III). The calculation runs on your device.
Tips for best results
- BMI does not apply as is to children, teenagers, pregnant women or very muscular people.
- Waist size is a useful addition: above 80 cm (31.5 in) for women and 94 cm (37 in) for men, heart risk increases.
- Weigh yourself in the morning before eating to compare values over time.
- A BMI outside the healthy range is a reason to talk to a doctor, not a diagnosis.
Common problems and fixes
I am very muscular and my BMI says overweight
That is BMI's limit: it does not tell muscle from fat. Waist size or body fat measurement says more.
The calculation is refused
In metric, enter height in centimeters (175, not 1.75). In imperial, enter feet and inches separately.
The result is for my child
Under 18, BMI is read on age and sex percentile charts: ask your pediatrician.
Frequently asked questions
What is a healthy BMI?
Between 18.5 and 24.9 for adults, according to the WHO.
How do I calculate my BMI?
Divide your weight in kg by your height in meters squared, or use 703 × lb / in².
Is BMI the same for men and women?
Yes, the WHO cut-offs are the same, even though fat distribution differs.
Is my data stored?
No. The calculation runs in your browser; only your preferred units are remembered on this device.
Related searches
Still stuck?
Ask on the forum: the category, the tool, your device sheet and the test result will be filled in for you.