Body Fat Calculator

Sex

Units

Height (in)

Measure standing height. Formula needs height in inches (auto-converted if metric).

Neck (in)

Circumference at the narrowest point (just below Adam’s apple).

Waist (in)

Horizontal at navel (no breath-holding).

Body Weight (optional) (lb)

Used to compute fat mass & lean mass if provided.

Uses the U.S. Navy method (log10-based). Ensure waist > neck (male) or waist+hip > neck (female).

Body Fat – Quick Cheat Sheet

Method: U.S. Navy circumference formula (inches). Metric is auto-converted.
Male formula: %BF = 86.010·log10(waist − neck) − 70.041·log10(height) + 36.76
Female formula: %BF = 163.205·log10(waist + hip − neck) − 97.684·log10(height) − 78.387
Units: Height/neck/waist(/hip) in inches for the formula. (1 in = 2.54 cm)
Measuring:
- Height: standing tall, no shoes.
- Neck: narrowest point (just below Adam’s apple).
- Waist: level at the navel, relaxed abdomen.
- Hip (female): largest circumference around buttocks.
Categories (ACE): Male: Essential 2–5, Athletes 6–13, Fitness 14–17, Average 18–24, Obese 25+. Female: Essential 10–13, Athletes 14–20, Fitness 21–24, Average 25–31, Obese 32+.
Notes: This is an estimate. Gold standards (DEXA, hydrostatic weighing) can differ.

Edge cases & tips

Ensure waist > neck (male) or waist + hip > neck (female) to avoid math errors.
Re-measure 2–3 times and average for consistency.
If you supply body weight, we’ll compute fat mass and lean mass.