What does this tool do?
BMI Calculator works out your Body Mass Index from your height and weight and places it into the underweight, normal, overweight or obese category. It gives a quick general sense of your weight status and supports both metric and imperial units.
How to use it
- Enter your values into the fields.
- The result is calculated instantly.
- Read or copy the result.
How to read your BMI
According to the World Health Organization: under 18.5 is underweight, 18.5–24.9 is normal, 25–29.9 is overweight and 30+ is obese. Because BMI does not distinguish muscle from fat, it can mislead for athletes — it is a general screening tool, not a medical diagnosis.
Frequently asked questions
What is the BMI formula?
BMI = weight (kg) / height (m)². For example, 70 kg and 1.75 m: 70 / (1.75 × 1.75) = 22.9. In imperial units: (weight lb / height in²) × 703.
Is BMI accurate for everyone?
No. BMI can mislead for muscular athletes, pregnant people, children and the elderly. Consult a doctor about your health — BMI is only a general indicator.
Is BMI Calculator free?
Yes. BMI Calculator and all 300+ tools on MagmaNex are completely free with no signup or account required.
Is my data safe?
Yes. Everything runs locally in your browser. The data you enter is never sent to a server, stored, or shared.
Does it work on mobile?
Yes. BMI Calculator works on phones, tablets and desktops — no app download needed.
🔒 Privacy: everything runs in your browser, your data is never sent to a server.