How to use the BMI calculator
- Choose Metric or Imperial units.
- Enter your height and weight.
- Read your BMI, your category on the colour scale, and the healthy weight range for your height.
What is BMI and how is it calculated?
Body Mass Index (BMI) estimates whether your weight is in a healthy range for your height. It’s widely used because it needs only two easy measurements.
imperial: BMI = 703 × weight(lb) ÷ height(in)²
BMI categories explained
| Category | BMI range |
|---|---|
| Underweight | Below 18.5 |
| Healthy weight | 18.5 – 24.9 |
| Overweight | 25.0 – 29.9 |
| Obese | 30.0 and above |
Limitations of BMI
BMI can mislabel some people. Athletes and very muscular individuals may have a high BMI despite low body fat, while older adults can have a “normal” BMI yet carry excess fat and little muscle. It also wasn’t designed for children or pregnancy, and some health bodies use lower thresholds for South Asian populations. Treat BMI as a starting point, not the whole picture — waist measurement and body-fat percentage add useful context.
Frequently asked questions
For most adults, 18.5 to 24.9 is the healthy range. This is the same for men and women — BMI uses only height and weight, not sex.
The formula and adult thresholds are the same for both. On average women carry more body fat than men at the same BMI, which is one reason BMI is only a screening tool.
Yes — especially if you’re muscular. BMI can’t tell muscle from fat. Measures like waist-to-height ratio and body-fat percentage give a fuller picture.
No. Everything is calculated in your browser and nothing is sent anywhere. See our privacy policy.