CALCULATOR 01
BMI Calculator
Body Mass Index from your height and weight, with WHO adult categories and optional Asian cut-offs.
Your BMI
Enter your height.
For general information only; not medical advice. Consult a qualified professional before making health decisions.
How this is calculated
BMI = weight (kg) ÷ height (m)²
Healthy weight range
18.5 × height (m)² to 24.9 × height (m)² (upper bound 22.9 with Asian cut-offs)
BMI Prime
BMI ÷ 25 (÷ 23 with Asian cut-offs)
WHO adult categories: under 18.5 underweight · 18.5–24.9 normal · 25.0–29.9 overweight · 30.0–34.9 obese class I · 35.0–39.9 obese class II · 40 and over obese class III.
Asian cut-offs: under 18.5 underweight · 18.5–22.9 normal · 23.0–27.4 overweight · 27.5 and over obese.
Sources
- World Health Organization, Body mass index (BMI) classification for adults.
- WHO Expert Consultation (2004), Appropriate body-mass index for Asian populations. Lancet 363:157–163.
About the bmi calculator
What BMI measures
Body Mass Index divides your weight by the square of your height. The result is a single number that lets you compare body size between people of different heights. It was designed to study populations, and at that level it works well: as average BMI rises, so do rates of type 2 diabetes, high blood pressure and heart disease.
For one person, BMI is a screening tool. It can prompt a closer look, but it can't diagnose anything on its own.
Read more about the BMI calculator
How the categories work
The World Health Organization groups adults into six bands: underweight below 18.5, normal from 18.5 to 24.9, overweight from 25 to 29.9, and three obesity classes starting at 30, 35 and 40. The healthy weight range shown above is simply the span of weights that would put you between 18.5 and 24.9 at your height. BMI Prime expresses your BMI as a fraction of the upper normal limit, so 1.0 means you're right at it.
Why there are Asian cut-offs
Research has found that people of Asian descent tend to carry more body fat, and face higher risk of type 2 diabetes and heart disease, at the same BMI as people of European descent. A 2004 WHO expert consultation suggested extra public-health action points at 23 and 27.5 for Asian populations. Many doctors in India and across Asia use these lower cut-offs, so the calculator lets you switch to them.
Limitations
BMI can't tell muscle from fat, and it says nothing about where fat is stored. A muscular athlete can be classed as overweight while being lean, and an older adult can have a normal BMI with little muscle. Waist size and body fat percentage add useful context.
The adult categories don't apply during pregnancy or to anyone under 18. Children and teenagers need age- and sex-specific percentile charts.
Frequently asked questions
What is a healthy BMI for adults?
For most adults, the WHO classes a BMI of 18.5 to 24.9 as normal weight. With Asian cut-offs, the normal range is 18.5 to 22.9.
Is BMI accurate for muscular people?
Not always. BMI can't tell muscle from fat, so people with a lot of muscle can have a high BMI while carrying little fat. A body fat estimate or a waist measurement gives more context.
Should I use the Asian BMI cut-offs?
If you are of South Asian, East Asian or Southeast Asian descent, the lower cut-offs may better reflect your health risk, because the risk of type 2 diabetes and heart disease tends to rise at lower BMIs in these populations. Many doctors in India use them.
What is BMI Prime?
BMI Prime is your BMI divided by the upper limit of the normal range (25, or 23 with Asian cut-offs). A value of 1.0 sits exactly at that limit; below 1.0 is under it.
Can children use this BMI calculator?
No. For under-18s, BMI has to be compared with age- and sex-specific percentile charts. A pediatrician can do this for you.