Body Fat Percentage Calculator — educational

Three accessible methods for estimating body-fat percentage — the US Navy circumference formula, Deurenberg's BMI-based formula, and Covert Bailey's quick index. Pick one, type your numbers, see a value and an ACE / ACSM classification band. Not a substitute for a DEXA scan or hydrostatic weighing.

Method
Units
Biological sex (the formulas use this; see disclaimer)
Body fat
—
%
ACE / ACSM band
—

ACE / ACSM body-fat bands (men)

2 – 5 % Essential
6 – 13 % Athletes
14 – 17 % Fitness
18 – 24 % Average
25 % + Above average

Bands reflect population averages. Athletes and people with high muscle mass frequently land outside "essential" or "athletes" without health consequence. Bands are not a personal health verdict.

How these formulas work, and what they don't measure

US Navy circumference (Hodgdon & Beckett, 1984) uses neck and waist (and hip for women) at well-defined measurement points, plus height, in a log-linear formula. Reasonably accurate (±3 % body fat) when measurements are taken carefully — snug tape, level surface, normal breathing, no clothing.

Deurenberg BMI-based (1991) uses only age, sex, and BMI. Convenient when only height and weight are known. Wider error band (±4–5 % body fat) because it does not measure body composition — only a height/weight ratio.

Covert Bailey's index is a rough rule-of-thumb: (weight − waist) × 100 / weight. Sex-agnostic and quick, but it was never validated against a published cohort. Use only as a sanity check.

What none of these measure: visceral vs subcutaneous fat distribution, muscle mass, bone density, metabolic health, fitness, or any individual health outcome. None is a substitute for a DEXA scan, hydrostatic weighing, BodPod, or a qualified clinician's assessment.

Why these bands differ for men and women: essential fat is roughly 2–5 % for men and 10–13 % for women (reflecting reproductive and hormonal physiology). The ACE / ACSM cut-points encode that difference.

For a fuller picture, talk to a doctor about body composition, waist circumference, blood pressure, cholesterol, blood glucose, and family history.