About this calculator
Body fat percentage is a far better indicator of health and composition than weight, because muscle and fat weigh differently at the same scale reading. The US Navy method uses circumference measurements, which need only a tape measure and about two minutes.
How it works
The formula uses height, neck, and waist, plus hips for women, and returns an estimated body fat percentage. Enter your body weight as well to see lean mass and fat mass. Measure at the same time of day to keep results comparable, since measurements shift through the day.
Frequently asked questions
What is a healthy body fat percentage?
For men, roughly 10 to 20% is considered athletic and 21 to 24% is average fitness. For women, 16 to 25% is athletic and 26 to 31% is average. Ranges vary widely with age and training status.
How accurate is a body fat calculator?
Circumference-based estimates are typically accurate to within 3 to 4 percentage points. They are far more reliable than consumer handheld bioimpedance scales, which can be off by 5 to 10 points due to hydration.
Where do I take the measurements?
Neck just below the Adam's apple. Waist at the navel, relaxed, not pulled in. Hips at the widest point, roughly at the hip bone. Keep the tape snug but not tight.
Does body fat percentage matter more than weight?
For health, yes. Two people at the same weight can have very different compositions, and the one with more muscle is generally healthier at the same weight.
Why do body fat readings fluctuate day to day?
Hydration, glycogen stores, sodium intake, digestion, and recent exercise all shift the reading by a couple of points. Look at the trend over weeks rather than a single measurement.
Is it possible to have low body fat and still be unhealthy?
Yes. Body fat below essential levels, roughly 5% for men and 12% for women, is dangerous and can affect hormones, bone density, and immunity. Essential fat cannot be safely reduced.