About Body Composition Calculators

Understanding your body composition is the first step toward better health. Our free body composition calculators help you measure BMI, body fat percentage, ideal weight, body surface area, waist-to-hip ratio and more. Whether you are starting a fitness journey or tracking progress, these tools give you accurate, instant results.

About Body Composition

Weight alone can’t tell you what you’re made of — and what you’re made of decides your health. Body composition is the breakdown of your weight into fat, muscle, bone, and water, and it explains why two people at the same weight can look and feel completely different. These seven calculators cover the full picture: BMI screens your weight-for-height against WHO categories (with Asian cutoffs noted), body fat percentage estimates your actual fat using the US Navy method, FFMI measures your muscularity and natural potential, BSA computes the clinical body-surface number used in hospitals, ideal weight gives a Devine-formula target, waist-to-hip ratio flags abdominal-obesity risk (especially relevant for South Asians), and bra sizing handles proper fit from two measurements. Use them together — a single number never tells the whole story.

FAQ

Which body composition number matters most?

For health: body fat percentage and waist-to-hip ratio. For fitness: FFMI and BMI trend. For clinical contexts: BSA. Most people should track at least two.

How often should I measure?

BMI monthly; body fat and waist-to-hip every 2–4 weeks; FFMI every couple of months. Consistency of method matters more than frequency.

Can I trust these if I’m very muscular or pregnant?

Muscular builds skew BMI and body-fat estimates slightly — pair methods. Pregnancy changes the rules for most of these; use obstetric guidance instead.

Explore more health calculators, or try our popular BMI Calculator, Body Fat Percentage Calculator and Ideal Weight Calculator.