BMI Calculator
This BMI calculator computes Body Mass Index from your weight and height in metric (kg, cm) or imperial (lb, in) units and shows the standard WHO category: underweight, normal, overweight or obese.
Underweight: < 18.5 | Normal: 18.5–24.9 | Overweight: 25–29.9 | Obese: ≥ 30
About this tool
This BMI calculator computes Body Mass Index from your weight and height in metric (kg, cm) or imperial (lb, in) units and shows the standard WHO category: underweight, normal, overweight or obese.
How to use it
- Choose metric (kg/cm) or imperial (lb/in).
- Enter your weight and height.
- Read your BMI and its weight category.
Good to know
- Metric: BMI = weight (kg) ÷ height (m)².
- Imperial: BMI = 703 × weight (lb) ÷ height (in)².
- WHO adult categories: under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, 30 and above obese.
- Example: 70 kg at 175 cm gives a BMI of about 22.9, in the normal range.
Runs entirely in your browser — nothing you enter is uploaded or stored.
Frequently asked questions
What is a healthy BMI?
For adults, the WHO classes a BMI of 18.5–24.9 as the normal range. Below 18.5 is underweight, 25–29.9 overweight and 30 or more obese.
Is BMI accurate for athletes?
Not always. BMI does not distinguish muscle from fat, so muscular people can score as overweight while being lean. Waist size or body-fat measurements add useful context.
Does BMI work for children?
Children and teenagers need age- and sex-specific BMI percentiles. The adult categories used here apply to people aged 18 and over.
Is BMI a diagnosis?
No. It is a screening number for weight relative to height. A health professional considers other factors before drawing conclusions.