Body & Fitness

Body Fat Percentage Calculator

Estimate body fat percentage using measurement-based formulas (US Navy method).

By Calculator Suite Pro Editorial Team | Last updated March 18, 2026

Browse more tools in All Tools.

SexHeight (cm)

Waist (cm)Neck (cm)

Body Fat %

12.0%

Method

US Navy

Note

Estimate

Use trends, not a single number.

Direct answer

Body Fat Percentage Calculator gives an instant result from your inputs. Body fat percentage estimates how much of your body weight is fat mass compared to total weight. Unlike BMI, body fat percentage aims to describe body composition more directly. Formula snapshot: It uses logarithms of measurement combinations (for example, waist minus neck). Example: Sex: Men, Height: 180cm, Waist: 90cm, Neck: 40cm -> Estimated body fat % shown.

About this calculator

Body fat percentage estimates how much of your body weight is fat mass compared to total weight. Unlike BMI, body fat percentage aims to describe body composition more directly.

This calculator uses the popular measurement-based US Navy method. It requires tape measurements (waist, neck, height, and hip for women). The result is an estimate, not a medical diagnosis.

For best accuracy, measure in the morning, keep the tape level, and avoid pulling it too tight. Small measurement changes can noticeably affect the result.

How it works

A quick explanation of the logic behind the results, so you can trust what you see.

The US Navy method estimates body density based on circumferences and height, then converts density into body fat percentage.
It uses logarithms of measurement combinations (for example, waist minus neck).
Because it is tape-based, the estimate depends strongly on consistent measuring technique.
This method is widely used for quick screening but can differ from DEXA, calipers, or hydrostatic tests.

Formula used

These are the core formulas and logic rules used by this calculator.

It uses logarithms of measurement combinations (for example, waist minus neck).
This method is widely used for quick screening but can differ from DEXA, calipers, or hydrostatic tests.

Common use cases

Below are common real-world scenarios where this calculator is useful.

Tracking body composition progress over time
Comparing fat loss phases vs maintenance phases
Setting realistic fitness goals
Estimating lean mass when paired with body weight
Checking progress beyond a scale number
Fitness coaching and check-ins
General health awareness (non-diagnostic)
Complementing BMI with a composition estimate

How to use

Select sex (men/women) because the formula differs.
Enter waist, neck, and height measurements.
If applicable, enter hip measurement (women).
Calculate to see estimated body fat percentage.
Re-check your measurements if the number looks unusually high/low.

Common mistakes to avoid

These are the issues that most often cause confusing results.

Measuring at different spots each time (inconsistent waist/neck location).
Pulling the tape too tight or leaving it too loose.
Not keeping the tape level around the body.
Entering height/waist/hip in the wrong units.
Using the men's formula for women or vice versa.
Comparing with other methods and expecting identical numbers (methods differ).

Tips and notes

Measure at the same time of day for consistent tracking.
Take 2-3 measurements and use the average to reduce error.
Use this number mainly to track trends, not as a one-time verdict.
Pair with Lean Body Mass calculator if you want a rough lean-mass estimate from weight.
If you want a simpler screening metric, check Waist-to-Height Ratio too.

Glossary

Quick definitions for common terms used in this calculator.

Body composition

The proportions of fat mass and lean mass in the body.

US Navy method

A tape-measurement based method to estimate body fat percentage.

Examples

Men example

Input: Sex: Men, Height: 180cm, Waist: 90cm, Neck: 40cm

Output: Estimated body fat % shown

Women example

Input: Sex: Women, Height: 165cm, Waist: 75cm, Hip: 95cm, Neck: 35cm

Output: Estimated body fat % shown

Trend tracking

Input: Repeat weekly with same measurement points

Output: Compare changes in % over time

FAQ

Is body fat percentage more accurate than BMI?

It can be more descriptive for body composition, but it is still an estimate. BMI and body fat percentage measure different things.

Why does the calculator ask for neck measurement?

The US Navy method uses neck circumference as part of the density estimate.

Do I need hip measurement?

Hip is used in the women's US Navy formula. Men typically do not need hip measurement for this method.

How accurate is this method?

It is a useful estimate for many people, but results can differ from lab methods. Use it mainly for consistent trend tracking.

Can I use this if I lift weights and have more muscle?

Yes. The method is measurement-based, but any single method can still be imperfect for individuals.

Does hydration affect results?

Hydration can affect body measurements slightly. Measuring under similar conditions improves consistency.

Is this calculator free to use?

Yes. This calculator is free to use without signup.

Can I use this calculator on mobile?

Yes. The calculator is mobile-friendly and works on desktop as well.

Last updated and references

Last updated: March 18, 2026

Reviewed by Calculator Suite Pro Editorial Team.

For sensitive health and finance topics, review official sources in addition to calculator outputs.

Related calculators

Explore related tools to solve similar problems without leaving the site.

On this page