Free BMI Calculator
Body Mass Index (BMI) is a quick screening number that compares your weight to your height. Enter your numbers below — everything is calculated in your browser, and nothing you type ever leaves this page.
Your BMI
🔒 Private: all math runs in your browser. Nothing is sent anywhere, stored, or tracked.
What the number means
- Underweight: BMI below 18.5
- Healthy range: BMI 18.5–24.9
- Overweight: BMI 25–29.9
- Obese: BMI 30 or above
These are the WHO cutoffs used worldwide. They describe populations, not individuals — a single number cannot tell you whether you are healthy.
What BMI cannot tell you
BMI does not measure body fat, muscle, bone density, or where fat sits on your body. A muscular person can land in the "overweight" band with very little body fat. An older adult can land in the "healthy" band while carrying more fat than is ideal. That is why BMI is best used as a starting point for a conversation with a clinician — not as a verdict on your body, and never as a reason to chase extreme goals.
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See plans & free trial →Frequently asked questions
What is a healthy BMI?
The WHO classifies BMI 18.5–24.9 as the healthy range for most adults. It is a population-level screening band, not a personal prescription — muscle, bone density, and body composition all affect what a healthy weight means for you.
Is BMI accurate?
BMI is a rough screening number. It does not measure body fat, muscle, or bone density, so athletic people can score as overweight while carrying little fat, and older adults can score healthy while carrying more fat. Treat it as one data point, not a verdict.
Does BMI work for everyone?
No. BMI cutoffs were developed for adults and are less meaningful for children, teenagers, pregnant people, and very muscular people. For personal guidance, talk to a clinician who can look at more than one number.
Is this BMI calculator private?
Yes. All math runs in your browser. Nothing you enter is sent anywhere, stored, or tracked.
Disclaimer: BMI is a general screening number, not a diagnosis. It does not account for muscle, bone density, or body composition. Not medical advice — talk to a clinician for personal guidance. This tool never recommends a target weight or extreme goals.