BMI Calculator
Calculate BMI, weight, or height from any two values.
BMI Classification (WHO)
| BMI | Classification |
|---|---|
| Under 18.5 | Underweight |
| 18.5 – 24.9 | Normal weight |
| 25.0 – 29.9 | Pre-obese (Overweight) |
| 30.0 – 34.9 | Obese class I |
| 35.0 – 39.9 | Obese class II |
| 40.0 and above | Obese class III |
A BMI between 18.5 and 24.9 is considered normal weight by WHO standards.
About This Tool
BMI, or Body Mass Index, is a widely used measure that estimates body fat based on your height and weight. While most BMI calculators only work one way, this tool lets you go in any direction — find your BMI, or work backwards to figure out a target weight or the height that corresponds to a given BMI.
Three ways to calculate:
- Find BMI — Enter your height and weight to see where you fall on the BMI scale.
- Find Weight — Have a target BMI in mind? Enter it along with your height to see what you'd need to weigh.
- Find Height — Enter a BMI and weight to find the corresponding height.
The formula behind it all is straightforward: BMI = weight (kg) ÷ height (m)². Rearranging this equation gives you weight or height when you know the other two values.
Understanding BMI Categories
The WHO classifies a BMI under 18.5 as underweight, 18.5 to 24.9 as normal weight, 25 to 29.9 as pre-obese, and 30 or above as obese (in increasing severity from class I to III).
It's worth noting that BMI doesn't tell the whole story. It doesn't distinguish between muscle and fat, so a very athletic person might have a high BMI without being overweight. Think of it as a quick, useful snapshot rather than a definitive measure of health.
Privacy
All calculations happen right in your browser. No data is sent to any server.