⚖️ BMI Calculator
A quick, private BMI check with the WHO adult classification and the weight range considered healthy for your height.
| BMI | WHO classification (adults 18+) |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy weight |
| 25 – 29.9 | Overweight |
| 30 – 34.9 | Obesity class I |
| 35 – 39.9 | Obesity class II |
| 40 and above | Obesity class III |
BMI is a quick screening measure, not a diagnosis. It doesn't account for muscle mass, body composition, age, sex or ethnicity, and isn't intended for children, teens or pregnancy. Talk to a healthcare professional for a full picture.
How to use the BMI Calculator tool
- Choose metric or imperial units.
- Enter your weight and height.
- Read your BMI, category and healthy weight range – updated live.
Frequently asked questions
How is BMI calculated?
Weight in kilograms divided by height in metres squared. For 70 kg and 1.75 m: 70 ÷ 1.75² = 22.9.
What is a healthy BMI?
The WHO classes 18.5–24.9 as a healthy weight for adults, 25–29.9 as overweight and 30+ as obesity. Some health bodies use lower cut-offs for people of Asian descent.
Is BMI accurate?
It's a population-level screening tool. It can overestimate body fat in muscular people and underestimate it in older adults, so waist measurement and a clinician's assessment give a fuller picture.
Can children use this calculator?
No. Under-18s need age- and sex-specific BMI percentile charts; adult categories don't apply.