BMI Calculator
Calculate Body Mass Index (metric or imperial).
About BMI Calculator
Calculate your Body Mass Index from your height and weight using metric or imperial units. BMI is a simple screening number that relates weight to height and places the result into standard categories such as underweight, normal, overweight, and obese, giving a quick general indicator that health organizations use at a population level. Enter your measurements to see your BMI and where it falls. Keep in mind that BMI does not distinguish muscle from fat and is only a rough guide, not a diagnosis, so treat it as a starting point for a conversation with a professional. All calculations happen privately in your browser.
How to use this tool
- 1Choose metric or imperial units.
- 2Enter your height and weight.
- 3See your BMI value and category instantly.
BMI categories and what they mean
BMI (Body Mass Index) is your weight in kilograms divided by your height in meters squared. It's a screening number, not a diagnosis - it doesn't distinguish muscle from fat, so athletes often score 'overweight' while being very lean. Use it as a rough population-level indicator and talk to a clinician about anything it flags.
| BMI range | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 - 24.9 | Healthy weight |
| 25.0 - 29.9 | Overweight |
| 30.0 - 34.9 | Obesity (Class 1) |
| 35.0 - 39.9 | Obesity (Class 2) |
| 40.0 and above | Obesity (Class 3) |
Worked example: someone who is 175 cm (1.75 m) tall and weighs 72 kg has a BMI of 72 ÷ (1.75 × 1.75) = 23.5, which falls in the healthy range. In imperial units the formula is (weight in pounds × 703) ÷ (height in inches)².
Frequently asked questions
What is a healthy BMI range?
For most adults, a BMI between 18.5 and 24.9 is considered healthy. BMI is a general indicator and doesn't account for muscle mass.
Is BMI accurate for everyone?
BMI is a rough screening tool. Athletes and very muscular people may read as overweight despite low body fat. Consult a professional for a full assessment.