Body fat, from a tape measure
No calipers, no scale tricks — just a few honest measurements.
Results update as you type 🥑
What body fat % tells you
Body fat percentage is the share of your weight that is fat rather than muscle, bone, organs and water. It explains body composition far better than weight or BMI alone.
The U.S. Navy method estimates it from height and tape measurements at the neck, waist (and hips for women). It is not lab-grade like a DEXA scan, but it is consistent — which is what matters for tracking change over time.
Measure first thing in the morning, relaxed, with the tape snug but not compressing. Track the trend over weeks, not day-to-day noise.
Common questions
How accurate is the Navy method?
Within roughly 3–4% of lab methods for most people. Less precise individually, but reliable for tracking change if you measure consistently.
What is a healthy body fat percentage?
Broadly, fitness range is ~14–17% (men) / ~21–24% (women); athletic is lower. Essential fat is ~3% (men) / ~12% (women).
Where exactly do I measure?
Neck below the larynx, waist at the navel (men) or narrowest point (women), hips at the widest point. Keep the tape level.
Is my data stored?
No. Everything is calculated in your browser. Nothing is sent to a server or saved.
Sources & references
- Mifflin MD, St Jeor ST, et al. “A new predictive equation for resting energy expenditure in healthy individuals.” Am J Clin Nutr. 1990;51(2):241–247.
- Frankenfield D, Roth-Yousey L, Compher C. “Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults.” J Am Diet Assoc. 2005;105(5):775–789.
This calculator provides estimates for general educational use and is not medical advice. Consult a qualified professional before making significant dietary changes.