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//// Health · Body Composition

Body Fat Calculator

US Navy circumference method — enter neck, abdomen, and hip measurements to get your body fat %, fat mass, lean mass, and fitness category.

Where this fits

❤️ HealthHouseholds

This tool sits in the health domain and connects best with the next tools in that decision lane.

Healthy BMI18.5 – 24.9
Daily Calories2,000 – 2,500
Sleep Cycle90 min

Body Fat (US Navy Method)

16.5%

Fitness(14–17%)
Biological Sex
Height
ft
in
lbs
in

Measure below the larynx, sloping slightly downward front

in

Measure at navel level, horizontally

Body Composition Breakdown

Body Fat
16.5%Fitness
Fat Mass
30.6 lbs13.9 kg
Lean Mass
154.4 lbs70.0 kg
BMI
26.5Body Mass Index

Male Body Fat Categories

Essential Fat< 6%
Athlete6–13%
Fitness ◀14–17%
Average18–24%
Obese≥ 25%
1

Step 1 — Convert height to total inches

height_in = (feet × 12) + inches

= (5 × 12) + 10

= 70 inches

2

Step 2 — US Navy male formula

%BF = 86.010 × log10(abdomen − neck) − 70.041 × log10(height_in) + 36.76

= 86.010 × log10(34 − 15.5) − 70.041 × log10(70) + 36.76 = 86.010 × log10(18.50) − 70.041 × log10(70) = 108.989 − 129.233 + 36.76

= 16.5% body fat

Hodgdon & Beckett, 1984 — U.S. Navy Body Fat Formula

3

Step 3 — Fat mass

fat_mass_lbs = weight × (body_fat% / 100)

= 185 × (16.5 / 100)

= 30.6 lbs of fat

4

Step 4 — Lean mass

lean_mass_lbs = weight − fat_mass

= 185 − 30.6

= 154.4 lbs lean mass

5

Step 5 — BMI

BMI = (weight_lbs × 703) / height_in²

= (185 × 703) / 70² = 130055 / 4900

= BMI 26.5

Key insight

Your 16.5% body fat puts you in the Fitness category. You carry 30.6 lbs of fat and 154.4 lbs of lean mass. The US Navy method has ±3–4% accuracy vs DEXA — it's best used for tracking trends over time.

#ShowYourWork

Measurement Tips

Measure in the morning before eating. Pull the tape snug but not compressing. Take 3 readings and average them. The US Navy method typically reads within 3–4% of DEXA scan results — accurate enough for tracking progress.

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