BMI Calculator
Free BMI calculator for adults in kg/cm or lb/ft. See your body mass index, WHO category on a visual scale and a healthy weight range for your height. Private.
- No upload — 100% private
- Instant, on your device
- Free, no sign-up
- Works offline once loaded
How it works
How to use BMI Calculator
Choose metric (cm and kg) or imperial (feet, inches and pounds).
Enter your height and weight.
Read your BMI and see where it sits on the WHO scale.
Check the healthy weight range calculated for your height.
Why use it
Why use our BMI Calculator tool
Metric & imperial
Switch units any time — your values convert automatically.
Visual scale
A clear gauge shows your BMI against the WHO adult categories.
Healthy range for your height
See the weight range that corresponds to a BMI of 18.5–24.9.
Balanced context
Neutral wording and an honest note on what BMI can and can't tell you.
Nothing stored
Your height and weight stay on your device.
FAQ
Frequently asked questions
How is BMI calculated?
BMI is your weight in kilograms divided by your height in metres squared. In imperial units it is 703 × weight in pounds ÷ height in inches squared. Both give the same number.
What is a healthy BMI?
For most adults the World Health Organization classes 18.5 to 24.9 as the healthy range, 25 to 29.9 as overweight and 30 or above as obesity. Under 18.5 is classed as underweight.
Is BMI accurate for athletes?
Not always. BMI can't tell muscle from fat, so muscular people can show a high BMI while being very fit. Waist measurement or body-composition tests give extra context.
Can children use this calculator?
No. Children and teenagers are assessed with BMI-for-age percentiles that account for growth, so adult categories don't apply to them.
Why do some guidelines use different cut-offs?
Research shows health risks can begin at lower BMIs in some populations, so several Asian health bodies use 23 and 27.5 as action points. Your doctor can advise which applies to you.
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