How it works
- The US Navy formula turns tape measurements into body density, then into a body fat percentage.
- Men need height, waist and neck; women also need the hip at its widest point.
- Keep the tape level and relaxed, and use the same units throughout.
Good to know
- Categories are essential fat, athletes, fitness, average and obese, with different cut-offs for men and women.
- Athletes, pregnancy and illness need professional measurement such as DEXA.
- Nothing is stored or sent anywhere.
Standards and sources
Last reviewed October 10, 2026
Frequently asked questions
How accurate is it?
Within a few percentage points for most adults versus lab methods, but hydration, muscle and measurement error shift it. Athletes, pregnancy and illness need professional measurement.
How do I measure?
Waist at the navel, neck below the Adam’s apple, hip at the widest point for women. Keep the tape level and relaxed, and use the same units throughout.
What are the categories?
Essential fat, athletes, fitness, average and obese, with different cut-offs for men and women.