BMI Calculator
Easify your health — calculate your Body Mass Index.
Free BMI calculator with visual health report. Calculate your Body Mass Index, see your BMI category on an animated gauge, ideal weight range, BMR & daily calorie needs, body fat estimate, population comparison, BMI history chart, and personalized health recommendations.
BMI Categories
| Category | BMI Range | Status |
|---|
Your Ideal Weight Range
Estimated Health Metrics
How to Use
Select Metric (kg/cm) or Imperial (lbs/ft/in) using the toggle at the top. The calculator auto-converts if you switch mid-way.
Enter your height and weight. Optionally add your age, gender, and activity level to unlock BMR, daily calorie targets, and body fat estimates.
Your BMI appears on a color-coded semicircular gauge with an animated needle. The gauge shows all 7 BMI categories and highlights exactly where you fall.
Use the tabs to explore your ideal weight range, health metrics, population comparison, and personalized tips. Save results to track your BMI over time.
Body Mass Index (BMI) is a simple numeric measure of body fat based on a person's height and weight, developed by Belgian mathematician Adolphe Quetelet in the 1830s and later adopted by the World Health Organization as a population-level screening tool. The formula is BMI = weight (kg) ÷ height² (m²), or for imperial units: BMI = (weight in lbs × 703) ÷ height² (in²).
The WHO defines normal BMI as 18.5–24.9. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is classified as obese — split into three sub-classes. Our calculator shows all seven categories on an animated color-coded gauge so you can see at a glance where you stand.
Beyond the basic number, this calculator computes your Basal Metabolic Rate (BMR) using the clinically-validated Mifflin-St Jeor equation and your Total Daily Energy Expenditure (TDEE) based on your chosen activity level — both commonly used by nutritionists and fitness professionals. The body fat estimate uses the Deurenberg formula for a rough approximation. The ideal weight range section visualizes exactly how far your current weight sits from the normal BMI range. The population comparison tab shows how your BMI stacks up against global and regional averages. The BMI history tracker stores results in your browser's localStorage — data stays 100% private on your device.
Important limitations: BMI doesn't distinguish between muscle and fat — a muscular athlete may read "overweight" while being in peak health. It also doesn't account for age-related changes in body composition, ethnic differences in fat distribution, or bone density. For children under 20, BMI must be interpreted with age- and sex-specific percentile charts, which this calculator doesn't cover. Use BMI as a starting point for conversation with your healthcare provider, not as a standalone diagnosis.
Frequently Asked Questions
Body Mass Index (BMI) = weight (kg) / height (m²). For imperial: BMI = (lbs × 703) / (inches²). Example: 175 cm, 70 kg = BMI 22.9 (Normal Weight).
WHO defines healthy BMI as 18.5–24.9. Below 18.5 is underweight, 25–29.9 is overweight, 30+ is obese. These are general guidelines and don't account for muscle mass, age, or ethnicity.
No — muscle is denser than fat, so muscular athletes may show "overweight" BMI while having low body fat. For athletes, body fat percentage (DEXA scan) is more accurate.
BMR is calories your body burns at rest. TDEE = BMR × activity multiplier (1.2–1.9) for daily calorie needs. This calculator uses the Mifflin-St Jeor equation.
No. All results and history are stored only in your browser's localStorage. Nothing is sent to any server. Clearing browser data removes your history.