Body Mass Index Formula
BMI = weight (kg) / height (m)². For example, for 70 kg and 1.70 m, the result is approximately 24.2 kg/m².
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Body Mass Index (BMI) Calculator
Calculate your BMI from height and weight with a clear explanation of your result.
Calculations are approximate and do not replace personalized professional advice. Not intended for children, pregnant, or nursing individuals. For medical conditions or eating disorders, consult a qualified healthcare provider.
How we calculate
Calories: Mifflin-St Jeor formula multiplied by physical activity factor. Weight loss includes a 15% deficit; muscle gain includes a 300 kcal surplus. Macronutrient ratios can be customized with a specialist.
BMI: weight (kg) / height (m)². Adult categories: Underweight (< 18.5), Normal weight (18.5–24.9), Overweight (25–29.9), Obesity (≥ 30). Weight range uses 18.5 and 24.9 boundaries. CDC Adult BMI Categories.
Activity: MET × BMR / 24 × duration in hours. This is an estimate factoring in resting metabolic rate. MET coefficients are population averages.
BMI: Formula & Adult Standards
Body Mass Index evaluates the relationship between weight and height squared. It is a screening metric that helps identify general weight categories without diagnosing health.
How to Interpret BMI
Adult ranges: Underweight (< 18.5), Normal weight (18.5–24.9), Overweight (25–29.9), Obesity (≥ 30).
- formula is identical for adult men and women;
- age and body composition matter during interpretation;
- BMI cannot distinguish muscle mass from fat mass.
When BMI Is Not Enough
For athletes with high muscle mass and older adults, BMI alone may be less informative. For children, specialized growth charts must be used instead.
Frequently Asked Questions
How is Body Mass Index calculated?
Divide weight in kilograms by height in meters squared (kg/m²), or simply use our online calculator.
Does the formula differ for men and women?
The core formula is identical for all adults. Sex, age, and muscle composition are factored in during interpretation.
Does BMI show body fat percentage?
No. It only reflects total weight relative to height and cannot differentiate muscle from adipose tissue.