# Body Fat Percentage Calculator

> Free body fat percentage calculator. Enter sex, height, weight, and tape measurements to estimate body fat with the U.S. Navy method, plus fat mass and lean mass.

The scale tells you your total weight, not what it is made of. Enter a few tape measurements and this calculator estimates your body fat percentage with the U.S. Navy method, then splits your weight into fat mass and lean mass.

*Interactive tool: enter your values at https://toollantern.win/body-fat-percentage-calculator/ and results update instantly in your browser.*

## The Navy formula

The U.S. Navy method estimates body fat from tape measurements instead of a lab scan. It compares the circumference where you store fat (waist, plus hips for women) against a frame reference (neck and height). Men: 495 / (1.0324 - 0.19077 x log10(waist - neck) + 0.15456 x log10(height)) - 450. Women: 495 / (1.29579 - 0.35004 x log10(waist + hip - neck) + 0.22100 x log10(height)) - 450. All measurements in centimeters.

## How to measure

Measure in the morning, standing relaxed, the tape snug but not compressing the skin. Neck: just below the Adam's apple. Waist: at the narrowest point, usually around the navel for men. Hips (women): at the widest point. Take each measurement twice and use the average.

## Worked example

**Man**, height **180 cm**, neck **40 cm**, waist **90 cm**, weight **85 kg**: waist - neck = 50, log10(50) = 1.699, log10(180) = 2.255. Density term = 1.0324 - 0.19077 x 1.699 + 0.15456 x 2.255 = 1.0569. Body fat = 495 / 1.0569 - 450 = **18.4%**. Fat mass = 85 x 0.184 = **15.6 kg**, lean mass = **69.4 kg**, category **Average**.

## What to do with the number

Body fat percentage tells you whether a change in weight is fat or muscle. Pair it with the [TDEE calculator](/tdee-calculator/) to set a calorie target, then the [macro calculator](/macro-calculator/) to split those calories into protein, carbs, and fat. Tape-method estimates usually land within 3 to 4 percentage points of lab measurements, close enough to track trends over weeks.

## Frequently asked questions
### How accurate is the Navy body fat method?

Studies put it within about 3 to 4 percentage points of lab methods like DEXA for most people. It is built for tracking change over time, not for diagnosing health.

### Why do women enter a hip measurement?

The women's formula includes hips because women typically store more fat around the hips and thighs. The men's formula skips it because male fat storage centers on the waist.

### Should I measure in inches or centimeters?

This calculator uses centimeters. If you measured in inches, multiply each measurement by 2.54 first.

### Is this medical advice?

No. This is a general fitness estimate, not medical advice. Talk to a doctor before acting on body composition numbers, especially if you have a health condition.

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Interactive version: https://toollantern.win/body-fat-percentage-calculator/