Use this free BMI calculator to find your body mass index in seconds and see whether you sit in the underweight, healthy, overweight or obese range. Unlike a basic BMI chart, this tool also estimates body fat percentage (US Navy method), lean mass, BMR (basal metabolic rate) and TDEE (total daily energy expenditure), so you get a complete body-composition picture from height, weight, age, sex and a few measurements.
BMI is a screening number, not a diagnosis: athletes with high muscle mass can score "overweight" while carrying little fat, and older adults can hide low muscle behind a "healthy" BMI. That is why the calculator pairs BMI with body-fat and calorie targets, and why results are shown for both metric and imperial units.
How to use the bmi & body composition calculator
- 1Choose metric (kg/cm) or imperial (lb/ft) units.
- 2Enter height, weight, age and sex; add waist, neck and hip measurements for body-fat percentage.
- 3Pick your activity level to estimate TDEE and daily calorie targets.
- 4Read your BMI category, body-fat range, BMR/TDEE and the suggested calorie plan; save or export the result.
BMI & Body Composition Calculator โ frequently asked questions
How is BMI calculated?
BMI = weight (kg) รท height (m)ยฒ. In imperial units it is 703 ร weight (lb) รท height (in)ยฒ. A BMI of 18.5โ24.9 is classed as healthy, 25โ29.9 overweight and 30+ obese under WHO guidance.
Is BMI accurate for athletes or older adults?
Not on its own. Muscle weighs more than fat, so muscular people can read as overweight, while older adults can lose muscle without BMI changing. Use the body-fat percentage and waist measurements shown alongside BMI.
What is the difference between BMR and TDEE?
BMR is the energy your body burns at complete rest. TDEE multiplies BMR by an activity factor (1.2 sedentary to 1.9 very active) to estimate the calories you actually burn in a day โ the number to use for weight-loss or gain planning.
What BMI range is healthy for Indian and Asian adults?
Many Asian health bodies use lower cut-offs: 18.5โ22.9 healthy, 23โ24.9 overweight and 25+ obese, because health risk rises at a lower BMI. The calculator shows both WHO and Asian thresholds.
Is my data stored?
No. All calculations run in your browser; nothing is uploaded unless you choose to export or save a report.