What formula does the Body Fat Calculator use?

It uses the US Navy tape-measurement method (cm-based formula), which estimates body density from height, neck, and waist circumference for men, and height, neck, waist, and hip for women, then converts that to a body fat percentage.

How accurate is this body fat calculator?

The Navy method is a widely used field estimate, typically within a few percentage points of more precise methods like DEXA scans when measurements are taken carefully. It is a general estimate, not a diagnostic or medical-grade measurement.

Why does the female calculation need a hip measurement?

The Navy formula for women is derived from waist plus hip minus neck, because fat distribution patterns differ from men. Men only need waist and neck.

What do the body fat categories mean?

The categories (essential fat, athletic, fitness, acceptable, obese) follow ACE (American Council on Exercise) reference ranges, which differ by sex. They are general guidelines, not medical thresholds.

Can I use the Body Fat Calculator in pounds and inches?

Yes. Switch the unit toggle to US units and enter height, neck, waist, hip, and weight in inches and pounds — the calculator converts everything internally.

Are my body measurements uploaded anywhere?

No. The Body Fat Calculator runs entirely in your browser. The measurements you enter never leave your device and are not uploaded to ArrayKit.

Body Fat Calculator Online

Estimate body fat percentage from tape measurements using the US Navy method, right in your browser. A general estimate, not medical advice.

The Body Fat Calculator runs entirely in your browser. The height, neck, waist, hip, and weight figures you enter never leave your device and nothing is uploaded to ArrayKit. This tool gives a general estimate only and is not medical advice.

Open the Lean Body Mass Calculator

About Body Fat Calculator

Body Fat Calculator estimates your body fat percentage using the US Navy tape-measurement method, which combines height, neck, and waist (plus hip for women) into a body-density formula. Choose metric or US units, enter your measurements, and get an instant body fat percentage, an ACE category from athletic to obese, and — if you add your weight — an estimated fat mass and lean mass split. It is useful for tracking body composition trends over time, setting a training or nutrition baseline, or comparing progress between check-ins without any special equipment beyond a tape measure. This is a general estimate from a widely used formula, not a clinical body-composition test or medical advice. Everything computes locally in your browser — your measurements stay on your device.

Features

Estimates body fat percentage from height, neck, and waist (plus hip for women)
Uses the standard US Navy tape-measurement formula
Switch between metric (cm/kg) and US (in/lb) units
Shows an ACE body-fat category from athletic to obese
Optional weight field adds estimated fat mass and lean mass
Copy a plain-text summary of every result with one click
Clear error messages when a measurement is missing or unrealistic
Runs entirely in your browser with no measurements sent anywhere

How to use the Body Fat Calculator

Select your sex and preferred unit system
Enter your height, neck, and waist measurements (add hip if female)
Optionally add your weight to see fat mass and lean mass
Read your body fat percentage and category, and copy the summary

Example

Input

male 180cm, neck 40, waist 85

Output

Body fat: ~16%

The US Navy formula turns height, neck, and waist into an estimated body fat percentage.

Common errors & troubleshooting

The Body Fat Calculator shows 'Waist must be larger than neck.' — The Navy formula depends on waist minus neck being positive. Double-check the waist measurement — it should be taken at the navel, not the narrowest point.
Female results show 'Enter a hip measurement greater than 0.' — The female formula needs waist + hip - neck, so a hip measurement is required. Measure around the widest part of the hips.
Result looks unrealistically high or low. — Make sure all measurements use the same unit (all cm or all inches) and that the unit toggle matches what you typed — mixing units skews the estimate significantly.
Fat mass and lean mass are not shown. — Those figures only appear when you fill in the optional weight field, since they are derived from body fat percentage times body weight.

Frequently asked questions

What formula does the Body Fat Calculator use?: It uses the US Navy tape-measurement method (cm-based formula), which estimates body density from height, neck, and waist circumference for men, and height, neck, waist, and hip for women, then converts that to a body fat percentage.
How accurate is this body fat calculator?: The Navy method is a widely used field estimate, typically within a few percentage points of more precise methods like DEXA scans when measurements are taken carefully. It is a general estimate, not a diagnostic or medical-grade measurement.
Why does the female calculation need a hip measurement?: The Navy formula for women is derived from waist plus hip minus neck, because fat distribution patterns differ from men. Men only need waist and neck.
What do the body fat categories mean?: The categories (essential fat, athletic, fitness, acceptable, obese) follow ACE (American Council on Exercise) reference ranges, which differ by sex. They are general guidelines, not medical thresholds.
Can I use the Body Fat Calculator in pounds and inches?: Yes. Switch the unit toggle to US units and enter height, neck, waist, hip, and weight in inches and pounds — the calculator converts everything internally.
Are my body measurements uploaded anywhere?: No. The Body Fat Calculator runs entirely in your browser. The measurements you enter never leave your device and are not uploaded to ArrayKit.

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