Quick Answer
How is BMI calculated?
// Answer
BMI is your weight in kilograms divided by your height in metres squared: BMI = kg ÷ m². For example, 70 kg at 1.75 m is 70 ÷ (1.75 × 1.75) = 22.9. In imperial units, BMI = (pounds ÷ inches²) × 703.
Body Mass Index is a quick screening number that estimates whether your weight is in a healthy range for your height. It is widely used because it needs only two easy measurements, though it does not directly measure body fat.
BMI categories
| Category | BMI range |
|---|---|
| Underweight | Below 18.5 |
| Normal weight | 18.5 – 24.9 |
| Overweight | 25.0 – 29.9 |
| Obesity | 30.0 and above |
Why use this tool
A private health check
This BMI calculator runs entirely on your device — your height and weight are never uploaded. BMI is a useful starting point, but it does not account for muscle mass, bone density, or body composition, so treat it as one signal among many and consult a healthcare professional for personalised advice.
FAQ
Frequently asked questions
A BMI between 18.5 and 24.9 is generally considered a healthy weight for most adults.
Divide your weight in pounds by your height in inches squared, then multiply by 703.
BMI is a useful general screening tool but does not measure body fat directly, so it can be misleading for athletes with high muscle mass or for older adults.
Yes. All calculations happen in your browser and nothing you enter is uploaded or stored on a server.
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