Body Fat Calculator
This estimates your body fat percentage from three tape measurements using the US Navy method, developed by the Naval Health Research Center. It needs no special equipment, just a soft tape measure, and it's accurate enough to track progress over time.
How to measure
- Neck: just below the larynx, with the tape sloping slightly down to the front.
- Waist: at the navel for both sexes, tape level all the way round. Breathe out normally; don't suck in.
- Hips (women): around the widest part of the hips and buttocks.
Measure snug but not tight, and take each measurement twice, using the average. Consistency matters more than perfection: measure the same way each time so the trend is meaningful.
What the number means
Body fat percentage tells you what weight alone can't: how much of you is fat versus muscle, bone and organs. Two people at the same weight can look completely different depending on this. For tracking fat loss it's often more useful than the scale, because it shows whether you're losing fat or muscle.
Common questions
How accurate is the US Navy method?
It's an estimate, typically within about 3–4% of a DEXA scan for most people. Its real strength is consistency: measured the same way over time, it tracks your progress reliably even if the absolute number is slightly off.
Why does the waist measurement matter so much?
Waist circumference reflects abdominal fat, which the formula uses as its main input. This is also why the method can misread very muscular or very lean people at the extremes.
What body fat should I aim for?
For visible fitness, roughly 10–15% for men and 18–24% for women. Below the 'athletic' range is hard to maintain and not necessarily healthier. Essential fat (about 3–5% men, 10–13% women) is the minimum to function.
Want the full plan, not just a number?
Lean28 turns these numbers into a 28-day meal and workout plan, free.
Build my free planSources
- Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, DC: National Academies Press; 2005. Source
This calculator is general information, not medical advice, and its results are estimates for healthy adults. Speak to a doctor or registered dietitian before making significant changes, especially if you are pregnant or breastfeeding, under 18, or manage a medical condition.
