# Body Fat Calculator

> Estimate body-fat percentage with the U.S. Navy circumference method and compare it with a BMI-based estimate.

Page: https://askcalculators.com/calculator/body-fat-calculator/
Definition: https://askcalculators.com/calculator/body-fat-calculator/definition.json
JSON Schema: https://askcalculators.com/calculator/body-fat-calculator/schema.json
Version: 2.0.0
Maintained by: AskCalculators (software project; not a credentialed reviewer)
Qualified review: pending. Automated checks do not establish professional approval.
Page status: Live
Review status: Pending

## Use
Open the calculator page and enter values. Query-string parameters can restore and bookmark a calculation.
Example: https://askcalculators.com/calculator/body-fat-calculator/?unitSystem=metric&sex=male&age=30&weightKg=80&heightCm=180&neckCm=39&waistCm=90&hipCm=100

## Inputs
- unitSystem: Units; type=select; required; default=metric; values=metric|imperial
- sex: Sex used by equation; type=select; required; default=male; values=male|female
- age: Age; type=number; required; default=30; min=18; max=100
- weightKg: Weight; type=number; required; default=80; min=1; max=500; showWhen=unitSystem:metric
- heightCm: Height; type=number; required; default=180; min=50; max=300; showWhen=unitSystem:metric
- neckCm: Neck circumference; type=number; required; default=39; min=10; max=100; showWhen=unitSystem:metric
- waistCm: Waist circumference; type=number; required; default=90; min=20; max=300; showWhen=unitSystem:metric
- hipCm: Hip circumference (used for female equation); type=number; required; default=100; min=20; max=300; showWhen=unitSystem:metric
- weightLb: Weight; type=number; required; default=176; min=2; max=1100; showWhen=unitSystem:imperial
- feet: Height feet; type=number; required; default=5; min=1; max=9; showWhen=unitSystem:imperial
- inches: Height inches; type=number; required; default=11; min=0; max=11.9; showWhen=unitSystem:imperial
- neckIn: Neck circumference; type=number; required; default=15.4; min=4; max=40; showWhen=unitSystem:imperial
- waistIn: Waist circumference; type=number; required; default=35.4; min=8; max=120; showWhen=unitSystem:imperial
- hipIn: Hip circumference (used for female equation); type=number; required; default=39.4; min=8; max=120; showWhen=unitSystem:imperial

## Outputs
- bodyFat: Navy body-fat estimate; format=percent; primary
- category: Body-fat category; format=text
- bmiEstimate: BMI-based estimate; format=percent
- fatMass: Estimated fat mass; format=text
- leanMass: Estimated lean mass; format=text
- bmi: BMI; format=number

## Formula
U.S. Navy circumference equations use log10 of height and sex-specific circumference combinations; BMI estimate = 1.2×BMI + 0.23×age − 10.8×male − 5.4.

## Rules
- Empty optional inputs are undefined, not zero.
- Hidden conditional inputs are ignored.
- Do not invent missing required inputs.

Notice: Circumference methods estimate body composition and are not diagnostic measurements.