Body Fat Calculator - Estimate Your Body Fat Percentage

A free, accessible calculator to estimate body fat percentage (BFP) using the U.S. Navy method or BMI. Includes formulas, health charts, and step-by-step examples.

Full original guide (expanded)

Audit: Complete

Formula (LaTeX) + variables + units

This section shows the formulas used by the calculator engine, plus variable definitions and units.

Formula (extracted LaTeX)

\[BFP \% = 86.010 \times \log_{10}(\text{waist}_{cm} - \text{neck}_{cm}) - 70.041 \times \log_{10}(\text{height}_{cm}) + 36.76\]

BFP \% = 86.010 \times \log_{10}(\text{waist}_{cm} - \text{neck}_{cm}) - 70.041 \times \log_{10}(\text{height}_{cm}) + 36.76

Formula (extracted LaTeX)

\[BFP \% = 163.205 \times \log_{10}(\text{waist}_{cm} + \text{hip}_{cm} - \text{neck}_{cm}) - 97.684 \times \log_{10}(\text{height}_{cm}) - 78.387\]

BFP \% = 163.205 \times \log_{10}(\text{waist}_{cm} + \text{hip}_{cm} - \text{neck}_{cm}) - 97.684 \times \log_{10}(\text{height}_{cm}) - 78.387

Formula (extracted LaTeX)

\[BMI = \frac{\text{weight}_{kg}}{\text{height}_m^2}\]

BMI = \frac{\text{weight}_{kg}}{\text{height}_m^2}

Formula (extracted LaTeX)

\[BFP \% = (1.20 \times BMI) + (0.23 \times \text{Age}) - (10.8 \times \text{Gender}) - 5.4\]

BFP \% = (1.20 \times BMI) + (0.23 \times \text{Age}) - (10.8 \times \text{Gender}) - 5.4

Formula (extracted LaTeX)

\[\text{Fat Mass} = \text{Total Weight} \times (BFP \% / 100)\]

\text{Fat Mass} = \text{Total Weight} \times (BFP \% / 100)

Formula (extracted LaTeX)

\[\text{Lean Body Mass} = \text{Total Weight} - \text{Fat Mass}\]

\text{Lean Body Mass} = \text{Total Weight} - \text{Fat Mass}

Formula (extracted text)

$BFP \% = 86.010 \times \log_{10}(\text{waist}_{cm} - \text{neck}_{cm}) - 70.041 \times \log_{10}(\text{height}_{cm}) + 36.76$

Formula (extracted text)

$BFP \% = 163.205 \times \log_{10}(\text{waist}_{cm} + \text{hip}_{cm} - \text{neck}_{cm}) - 97.684 \times \log_{10}(\text{height}_{cm}) - 78.387$

Formula (extracted text)

$BMI = \frac{\text{weight}_{kg}}{\text{height}_m^2}$

Formula (extracted text)

$BFP \% = (1.20 \times BMI) + (0.23 \times \text{Age}) - (10.8 \times \text{Gender}) - 5.4$

Variables and units

No variables provided in audit spec.

Sources (authoritative):

Home — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/
Health & Fitness — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/health-fitness
Diet & Nutrition — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/subcategories/diet-nutrition
BMI Calculator — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/bmi-calculator
BMR Calculator — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/bmr
TDEE Calculator — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/tdee
Ideal Weight Calculator — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/ideal-weight

Changelog

Version: 0.1.0-draft
Last code update: 2026-01-19

0.1.0-draft · 2026-01-19

Initial audit spec draft generated from HTML extraction (review required).
Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
Confirm sources are authoritative and relevant to the calculator methodology.

Verified by Ugo Candido on 2026-01-19
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Formulas

(Formulas preserved from original page content, if present.)

Version 0.1.0-draft

Citations

Add authoritative sources relevant to this calculator (standards bodies, manuals, official docs).

Changelog

0.1.0-draft — 2026-01-19: Initial draft (review required).