BMI Calculator
Work out your body mass index in metric or imperial units, see which category you fall into, and find the healthy weight range for your height.
النسخة العربية ↗How to use the BMI calculator
- Choose metric (kg and cm) or imperial (pounds, feet and inches).
- Enter your weight and height. The result updates as you type.
- See your BMI, your category on the colour scale, and the weight range that counts as healthy for your height.
The BMI formula
Body mass index compares your weight with your height. It was designed for large population studies, and doctors use it as a quick first check.
BMI = 703 × weight (lb) ÷ height (in)²
Example: 70 kg and 1.70 m gives 70 ÷ (1.70 × 1.70) = 24.2, which sits in the healthy range.
BMI categories for adults
| BMI | Category (WHO) |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy weight |
| 25.0 – 29.9 | Overweight |
| 30.0 and above | Obesity |
A World Health Organization expert group has noted that health risks can start at lower BMI values in some Asian populations, so some countries use a lower threshold for overweight. If you are unsure which applies to you, ask your doctor.
What BMI does not tell you
BMI cannot tell muscle from fat. A rugby player and a sedentary office worker can have the same BMI with very different health. It also says nothing about where fat is stored, and fat around the waist carries more risk than fat elsewhere. That is why many clinicians pair BMI with a waist measurement.
Frequently asked questions
What is a healthy BMI?
For most adults, a BMI from 18.5 to 24.9 is considered a healthy weight range.
Is BMI accurate for athletes?
Not always. Muscle is dense, so very muscular people can have a high BMI without excess fat.
How do I calculate BMI in pounds and inches?
Multiply your weight in pounds by 703, then divide by your height in inches squared. The imperial mode does this for you.
Does BMI differ for men and women?
The adult formula and categories are the same for both sexes, although body fat at a given BMI tends to differ.
What should I do if my BMI is outside the healthy range?
Use it as a prompt for a conversation with your doctor, who can look at your overall health rather than a single number.
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