Body fat calculator
The US Navy tape method: three measurements, one number, and the category it puts you in. Then the transformation page for the next milestone down.
How it works
Hodgdon and Beckett fitted the formula for the US Navy in 1984 from circumference measurements against underwater weighing. For men it uses waist minus neck against height; for women, waist plus hips minus neck. It is the same method most online calculators use, and the same one the Navy still uses for fitness standards.
What the categories mean
- Essential fat (men under 6%, women under 14%): stage conditioning, not a place to live.
- Athlete (6–13% / 14–20%): visible abs and definition. See 10% and 12%.
- Fitness (14–17% / 21–24%): lean and athletic. See 15%.
- Average (18–24% / 25–31%): the most common starting point in the app. See transformations from overweight.
From number to picture
Once you know where you are, the time calculator tells you how long the next milestone takes, and LiftLooks shows you what it looks like on your own photo.
Questions
How accurate is the Navy body fat method?
Within about 3–4 percentage points of a DEXA scan for most people, which is similar to calipers in practised hands and better than most home scales. It is least accurate at the extremes: very lean or very muscular people tend to read a little high.
How do I measure correctly?
Use a soft tape, snug but not compressing. Neck: just below the larynx, tape sloping slightly downward at the front. Waist for men: at the navel, relaxed, after a normal exhale. Waist for women: at the narrowest point; hips at the widest. Measure at the same time of day for tracking.
What body fat percentage shows abs?
Upper abs typically show around 15% for men and 23% for women; a full six-pack in normal light is closer to 12% and 20%. The 15, 12, 10, and 8% pages show each level rendered on real photos.
See your next 5% on your body.
Get the app, upload one photo, and see this transformation rendered on your own frame.
