📏 Body Fat & BMI Calculator

BMI is a quick height-to-weight ratio; body-fat percentage tells you how much of your weight is actually fat. Enter a few measurements to estimate both, plus your lean body mass.

Sex

Height

Weight

Waist (at navel)

Neck (below larynx)

Measure relaxed, tape snug but not compressing.

BMI

24.5

Normal

Body fat

16.9%

Fitness

Fat mass

12.7 kg

Lean mass

62.3 kg

BMI vs. body fat

BMI ignores body composition, so a muscular person can read as “overweight” while carrying low fat. Body-fat percentage is more useful for training goals. This tool uses the US Navy circumference method — quick and free, with a typical error of ±3–4% versus a DEXA scan. Use it to track the trend over weeks, not as an exact figure.

These calculators give population-level estimates for healthy adults and are not medical advice. If you are pregnant, under 18, or managing a health condition, talk to a professional.