The formula
BMI = weight in kilograms ÷ (height in metres)²
Example: 70 kg and 1.75 m: 70 ÷ (1.75 × 1.75) = 70 ÷ 3.0625 = 22.9.
In imperial units: BMI = 703 × weight in pounds ÷ (height in inches)².
Standard adult categories
| BMI | Category (WHO) |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy weight |
| 25.0 – 29.9 | Overweight |
| 30.0 and above | Obesity |
For a height of 1.75 m, the healthy-weight range of 18.5–24.9 corresponds to roughly 56.7–76.3 kg.
Some health authorities use lower thresholds for people of South Asian, Chinese and some other backgrounds, because health risks can rise at lower BMI values. Ask a health professional which applies to you.
Calculate it
- In the BMI Calculator, choose metric or imperial units.
- Enter height and weight. In imperial mode, weight can be in stone and pounds or pounds only.
- Optionally enter your age; adult categories apply from age 20 (18 in some countries).
- Read your BMI, its category and the healthy-weight range for your height.
Healthy-weight range by height
The table shows the weight range that corresponds to a BMI of 18.5–24.9 at common adult heights, using the standard WHO categories.
| Height | Weight range (kg) |
|---|---|
| 1.55 m (5 ft 1 in) | 44.4 – 59.8 |
| 1.60 m (5 ft 3 in) | 47.4 – 63.7 |
| 1.65 m (5 ft 5 in) | 50.4 – 67.8 |
| 1.70 m (5 ft 7 in) | 53.5 – 72.0 |
| 1.75 m (5 ft 9 in) | 56.7 – 76.3 |
| 1.80 m (5 ft 11 in) | 59.9 – 80.7 |
| 1.85 m (6 ft 1 in) | 63.3 – 85.2 |
Feet and inches are rounded to the nearest inch. For your exact height, the calculator shows the range directly.
What BMI does not tell you
- It does not distinguish muscle from fat, so muscular people can be classed as overweight.
- It does not show where fat is stored; waist measurement is a useful additional indicator.
- It does not account for age-related changes, ethnicity or body composition.
- Adult categories do not apply to children, teenagers or during pregnancy.
BMI is general information, not a diagnosis. Speak to a doctor or other qualified professional about your health.
Frequently asked questions
Is BMI accurate for athletes?
Often not. High muscle mass increases weight without increasing health risk, so BMI can overstate risk for very muscular people.
Is my data saved?
No. The calculation runs in your browser and nothing is stored or sent.