BMI Calculator.
Height and weight → BMI with the WHO adult category.
| Category | BMI |
|---|---|
| Underweight | Below 18.5 |
| Normal range | 18.5 to 24.9 |
| Pre-obese (overweight) | 25.0 to 29.9 |
| Obese class I | 30.0 to 34.9 |
| Obese class II | 35.0 to 39.9 |
| Obese class III | 40.0 or more |
How it works.
Choose units
Use metric (kg and cm) or imperial (lb, feet and inches). Anything already typed is converted when you switch, using the exact factors 1 lb = 0.45359237 kg and 1 in = 2.54 cm.
Enter height and weight
BMI is weight in kilograms divided by height in metres squared. The result updates as you type.
Read the WHO category
The table uses the World Health Organization's adult cut-offs: below 18.5 underweight, 18.5 to 24.9 normal range, 25 to 29.9 pre-obese, and 30 or more obese, split into classes I, II and III.
Read the limits too
BMI cannot tell muscle from fat and its link to risk varies with age and ethnicity. The weight range shown is arithmetic on the cut-offs at your height, not a goal.
FAQ.
How is BMI calculated?
Weight in kilograms divided by height in metres squared. Someone 1.75 m tall who weighs 70 kg has a BMI of 70 ÷ (1.75 × 1.75), which is 22.9 kg/m².
Where do the BMI categories come from?
From the World Health Organization's adult classification in its 2000 report Obesity: preventing and managing the global epidemic (WHO Technical Report Series 894): underweight below 18.5, normal range 18.5 to 24.9, pre-obese 25 to 29.9, obese class I 30 to 34.9, class II 35 to 39.9, and class III 40 or more. The same cut-offs apply to adult men and women.
What are the limits of BMI?
BMI does not separate muscle from fat, so muscular people can read high, and it says nothing about where fat is carried. The link between BMI and health risk shifts with age, and a 2004 WHO expert consultation published in The Lancet found that in many Asian populations risk rises at lower BMI values than the standard cut-offs.
Can I use it for children or teenagers?
Not with these cut-offs. Children and teenagers are assessed against age and sex specific growth references (BMI for age), because body composition changes as they grow. Adult BMI categories also do not apply during pregnancy.
Is the weight range shown a target?
No. It is the range of weights that would give a BMI from 18.5 to 24.9 at the height you entered, worked out by arithmetic. It carries every limitation of BMI itself and is not a goal for anyone in particular.
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