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Body Fat Percentage Calculator

Estimate your body fat percentage with the US Navy measurement method or a quick height and weight formula. See your reference range, fat mass, and lean mass without signing up.

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Metric and US units
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The basics

How to Calculate Body Fat Percentage

Body fat percentage is the share of your total body weight made up of fat. Unlike BMI, it separates estimated fat mass from lean mass such as muscle, bone, organs, and body water.

1. Choose a method

Use the US Navy method when you have a flexible tape measure. Choose the height and weight estimate when you only know your basic measurements.

2. Measure consistently

Stand relaxed, keep the tape level, and measure against the skin without compressing it. Repeating each circumference two or three times can reduce simple tape-placement errors.

3. Read the estimate in context

A single number is less useful than a consistent trend. Compare repeat measurements taken under similar conditions rather than chasing small day-to-day changes.

4. Remember the margin of error

Online formulas estimate body composition; they do not directly scan body tissue. Hydration, tape tension, anatomy, and the selected equation all affect the result.

Measurement method

US Navy Body Fat Percentage Calculator Method

The Navy circumference method estimates body fat from height and a small set of tape measurements. It usually reflects body shape better than a height-and-weight formula, while remaining easy to use at home.

Neck

Measure just below the larynx, with the tape sloping slightly downward at the front. Keep your shoulders relaxed and look straight ahead.

Waist

For the Navy equation, measure the abdominal circumference at the navel after a normal exhale. Keep the tape horizontal and do not pull your stomach inward.

Hip

The female Navy formula also uses hip circumference. Measure around the widest part of the buttocks while keeping the tape parallel to the floor.

How the equation works: the method uses logarithmic relationships between circumference differences and height. The calculator converts metric values internally so metric and US unit inputs produce equivalent estimates.

Quick method

Height and Weight Estimate for Body Fat Percentage

If you do not have a tape measure, the height and weight option first calculates BMI and then applies an adult research equation using age and formula sex.

Estimated body fat % = 1.20 × BMI + 0.23 × age − 10.8 × sex − 5.4

In the published formula, sex is coded as 1 for the male equation and 0 for the female equation. This calculator labels that choice clearly because it is a mathematical input, not a statement about gender identity.

When is the height and weight estimate useful?

It is useful for a fast baseline, population-level comparisons, or situations where circumference measurements are unavailable. It can be misleading for highly muscular people, older adults with low muscle mass, pregnant people, and anyone whose body composition differs substantially from the population used to develop the equation.

Reference ranges

Body Fat Percentage Chart by Age and Sex

The ranges below are commonly cited healthy reference intervals derived from research connecting BMI guidelines with measured body fat. They are context, not a diagnosis or a universal target.

Age	Male formula range	Female formula range
20–39	8–19%	21–32%
40–59	11–21%	23–33%
60–79	13–24%	24–35%

For ages 18–19 and 80–100, the calculator still provides an estimate but does not assign one of these research-based reference ranges.

Interpreting results

What Is an Ideal Body Fat Percentage?

There is no single ideal body fat percentage for every person. Age, biological characteristics, health history, sport, muscle mass, and the measurement method all change what a useful target looks like.

Use a range, not a magic number

Reference ranges are more honest than one exact target. A result near a boundary can also move between categories because online methods have measurement error.

Track changes consistently

If your goal is to monitor progress, use the same method, tape placement, time of day, and general hydration conditions each time.

Accuracy and limits

How Accurate Is This Calculator?

No online body fat percentage calculator is exact. The Navy method is generally more personalized than a BMI-based estimate, but both remain indirect methods.

What can change the result?

Tape placement, posture, breathing, clothing, hydration, recent meals, and rounding can all shift an estimate. The height-and-weight equation is also sensitive to unusually high or low muscle mass.

What is more accurate?

Clinical and laboratory options include DEXA, air displacement plethysmography, and professionally administered skinfold or bioimpedance assessments. Each has its own assumptions, costs, and sources of error.

Use this result as an estimate and trend-tracking tool. Consult a qualified healthcare professional when body composition is relevant to a medical concern, eating disorder, pregnancy, or treatment plan.

Formula differences

Body Fat Percentage for Men and Women

The equations use different circumference combinations because average fat distribution differs between the populations used to develop them.

The male Navy equation uses neck and waist measurements. The female Navy equation adds hip circumference. Reference ranges are also different because essential fat and typical body-fat distributions differ. These are limitations of the equations themselves; they do not capture every body, hormone profile, transition, or medical circumstance.

Common questions

Frequently Asked Questions

Can I calculate body fat percentage at home?

Yes. A flexible tape measure and the US Navy method offer a practical home estimate. Measure carefully and repeat the process under similar conditions.

Can height and weight alone calculate body fat?

They can produce a rough estimate through a BMI-based research equation, but height and weight cannot distinguish muscle from fat. Circumference or clinical measurements provide more body-specific information.

Is the Navy body fat method accurate?

It is useful for screening and repeat tracking, but it is still an estimate. Tape placement and differences in body shape can create several percentage points of variation.

Why does the female formula need a hip measurement?

The female Navy equation was developed using neck, waist, hip, and height. Omitting the hip measurement would mean using a different, unsupported equation.

Is body fat percentage better than BMI?

They answer different questions. BMI describes weight relative to height, while body fat percentage estimates how much weight is fat mass. Neither number alone describes overall health.

How often should I measure body fat?

For trend tracking, every two to four weeks is usually more informative than daily measurement. Short-term changes can reflect measurement noise rather than a true change in body fat.

Does the calculator store my measurements?

No. Calculation happens locally in your browser. This page does not require an account, upload your measurements, or save them in cookies.

Methodology

Sources and Medical Disclaimer

The height-and-weight estimate follows the adult Deurenberg BMI equation. The age- and sex-based context uses ranges reported by Gallagher and colleagues. The circumference calculation uses the commonly published US Navy equations.

Deurenberg P, Weststrate JA, Seidell JC. “Body mass index as a measure of body fatness: age- and sex-specific prediction formulas.” PubMed.
Gallagher D, et al. “Healthy percentage body fat ranges: an approach for developing guidelines based on body mass index.” PubMed.

This website provides educational estimates only. It does not diagnose a health condition, replace medical testing, or provide treatment or personalized weight loss advice.