Body Composition Calculator
Work out fat mass and lean mass from your weight and body fat percentage. Free.
Body composition calculator
This body composition calculator splits your weight into fat mass and lean (fat-free) mass. Enter your weight and your body fat percentage (from scales, calipers or another method). You get fat mass and lean mass in the same unit. Useful for tracking changes when dieting or training. Accuracy depends on how accurate your body fat % is.
Frequently Asked Questions
What is body composition?
Body composition is the breakdown of your body into fat mass and fat-free mass (lean mass: muscle, bone, water, etc.). Knowing it helps with fitness and health goals. It is often estimated from body fat percentage and weight.
How do I calculate body composition?
If you know your weight and body fat percentage, fat mass = weight × (body fat % / 100) and lean mass = weight − fat mass. This calculator does that. Body fat % can come from scales, calipers or other methods.
Is the body composition calculator free?
Yes. Free to use. Results depend on accuracy of your body fat percentage input.
What is a healthy body fat percentage?
Guidelines vary. Rough ranges for adults: men 10–20% often considered fit, 20–25% average; women 20–30% fit, 25–32% average. Too low or too high can have health implications; consult a professional for advice.
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<p>Calculator: <a href="https://onlinecalculator.co.uk/health/body-composition-calculator" target="_blank">Body Composition Calculator</a> - OnlineCalculator.co.uk</p>APA Style Citation:
OnlineCalculator.co.uk. (2025). Body Composition Calculator. Retrieved from https://onlinecalculator.co.uk/health/body-composition-calculatorNote: This calculator is free to use and reference. No permission required for educational or commercial citation.