How to Use the BMI Calculator: A Practical Guide
Who Calculator BMI comes up constantly in searches, and the answers online are usually either a one-line reply or a wal…
BMI Calculator
Calculate Body Mass Index from height and weight, and see which WHO category the result falls into.
kg / lb
cm / in
years
Body Mass Index
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The formula
BMI = weight(kg) / height(m)²
Every result on this page comes from this formula. Nothing is rounded until the final display, so figures match a spreadsheet to the cent.
How to use the BMI Calculator
- Choose metric or US units.
- Enter your weight and height.
- Read your BMI and the category it falls in, then compare it with the healthy weight range shown.
BMI Calculator — frequently asked questions
What is a healthy BMI?
The World Health Organization treats 18.5–24.9 as the healthy range, 25–29.9 as overweight and 30 or above as obese. Below 18.5 is classed as underweight.
Is BMI accurate for athletes?
Not always. BMI cannot separate muscle from fat, so muscular people are often classified as overweight while having low body fat. Body fat percentage and waist circumference give a fuller picture.
Does BMI work for children?
Children use age- and sex-specific BMI percentiles rather than the adult cut-offs, because body composition changes throughout growth.
Is this bmi calculator free to use?
Yes. Every calculator on the site is free, needs no sign-up, and runs entirely in your browser, so your figures never leave your device.
How accurate is the result?
The maths is exact for the formula shown on the page. Accuracy in the real world depends on your inputs and on assumptions the formula cannot see, so treat the output as a well-grounded estimate rather than a quote.
Related reading
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About this calculator
Written and reviewed by The Samsung Calculator editorial team. Every calculator is written against a published formula, reviewed against at least one independent reference implementation, and dated when it changes.
Last reviewed August 13, 2026 · Calculation runs client-side · No data collected · Report an error