Body Fat Percentage Calculator
What is Body Fat Percentage Calculator
This body fat calculator uses the US Navy circumference method, the same tape-measure formula the Navy has relied on for decades. Instead of a pinch test or an expensive scan, it estimates your body fat percentage from your height and a few tape measurements: your neck and waist, plus your hip if you are a woman. Enter your weight too and it splits the result into fat mass and lean mass. It is an estimate rather than a medical reading, so careful, consistent measuring is what makes it reliable.
How to use
- Pick your sex and switch between metric (cm/kg) and imperial (in/lbs) units.
- Measure your height and type it in.
- Wrap a tape around your neck and waist (and hips, for women), keeping it snug and level, then enter each value.
- Optionally add your body weight to see fat mass and lean mass alongside the percentage.
- Read your body fat percentage and the category band it falls into.
When to use it
Use it when you want a number that actually tracks your progress, since the scale alone hides whether you are losing fat or muscle. Measure once a week under the same conditions and watch the trend rather than a single reading. For example, a man 178 cm tall with a 40 cm neck and a 90 cm waist comes out around 18.7%, which lands in the Average range.
Frequently asked questions
How accurate is the US Navy body fat method?
For most people it lands within about 3 to 4% of clinical methods like a DEXA scan, as long as you measure carefully and consistently. It is less accurate at the extremes, for very lean athletes or people carrying a lot of fat, where the formula tends to drift.
What is a healthy body fat percentage?
For men, roughly 14 to 17% is considered fitness level and 18 to 24% is average. For women it is about 21 to 24% for fitness and 25 to 31% for average. Women naturally carry more essential fat than men, so a healthy female reading is always several points higher.
What body fat does a 178 cm man with a 40 cm neck and 90 cm waist have?
About 18.7%, which sits in the Average band for men. Change any single measurement, for instance trimming the waist to 85 cm, and the percentage drops noticeably, which is exactly why waist size is the number worth tracking.
What is the difference between fat mass and lean mass?
Fat mass is your weight multiplied by your body fat percentage, so an 80 kg person at 18.7% carries about 15 kg of fat. Lean mass is everything else: muscle, bone, organs and water. Adding your weight lets the calculator report both figures.
Can I share this tool with my inputs pre-filled?
Yes. The URL updates automatically as you type. Copy it from the address bar or use the Share button, and anyone who opens the link will see your exact inputs ready to go.
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