Body Fat Calculator
Estimate your body fat percentage using the U.S. Navy method. Get lean mass, fat mass, and fitness category.
Enter Your Values
Enter your values and press Calculate: you will get the result, its method, the inputs used and confidence, plus copy, print and share options.
How this calculator works
US Navy circumference body fatv1.0.0
Body fat from neck, waist (and hip for women) circumferences (Hodgdon & Beckett 1984).
- Applies to
- Adults
- Assumptions
- Careful, consistent circumference measurement technique
- Limitations
- Measurement technique dominates the error
- Output
- % body fat
- Last reviewed
- 2026-06-01
Relative Fat Mass (RFM)v1.0.0
Body fat estimate from height and waist circumference (Woolcott & Bergman 2018).
- Applies to
- Adults of various ethnicities (validated vs DXA)
- Assumptions
- Waist measured at the navel level
- Limitations
- Estimate error of several percentage points vs DXA
- Output
- % body fat
- Last reviewed
- 2026-06-01
Evidence Sources & Literature
- Naval Health Research Center. Prediction of percent body fat from circumferences (Hodgdon & Beckett). Report 84-29, 1984.
- Scientific Reports. Relative fat mass (RFM) as a new estimator of whole-body fat percentage. Sci Rep, 2018. doi:10.1038/s41598-018-29362-1.
About the Body Fat Calculator
Body fat percentage tells you what share of your weight is fat versus everything else (muscle, bone, water and organs), and it is often a more meaningful measure of health and fitness than weight or BMI alone. This calculator estimates your body fat using the US Navy method, which relies on a few simple tape-measure readings rather than special equipment.
I like body fat percentage because it gets at the thing people usually care about: composition, not just the number on the scale. Two people at the same weight can look and feel very different depending on how much of that weight is muscle, and this measure captures that.
Why composition beats weight alone
The scale tells you how heavy you are, but not what you are made of. Body fat percentage fills that gap. It is why someone can lose inches and get stronger while the scale barely moves, as they trade fat for muscle. Tracking body fat (or simply a tape measure) alongside weight gives a much truer picture of progress, and I have seen it keep people motivated when the scale alone would have discouraged them.
How the Navy method works
This calculator uses the US Navy circumference method, which estimates body fat from your height and a few tape measurements (neck and waist for everyone, plus hips for women). It is not as precise as a lab scan, but it is free, repeatable at home, and good at tracking change over time, which is what most people actually need. Measuring consistently, same spot, same time of day, makes your trend reliable.
Healthy ranges
Healthy body fat differs by sex because women naturally carry more essential fat. As a rough guide, many sources put a healthy range around 21 to 33 percent for women and 8 to 20 percent for men, varying with age and athletic level. Very low body fat is not healthier, it carries its own risks, so the goal is a sensible range, not the lowest possible number. The calculator gives your estimate; treat it as a trend tracker.
Using it well
Because this is an estimate, the single most valuable thing you can do is measure consistently and watch the direction of travel over weeks, not obsess over a single reading. Combine it with strength training and adequate protein if your goal is to lose fat while keeping muscle. And remember it is one tool among several, useful, but not the whole story of your health.
Dietitian Insight: Body fat percentage measures the proportion of adipose tissue relative to total body mass. Explore essential versus fitness ranges in our guide to understanding body fat categories, or test military circumference standards with our Army body fat calculator.
Sources & method
This calculator uses established, peer-reviewed formulas and reference ranges from recognized health and nutrition authorities. Results are estimates for general education, not a medical diagnosis. For decisions about your health, consult a qualified clinician. Reviewed by Macro & Meals Editorial Team, Content editor.
Frequently Asked Questions
What is a healthy body fat percentage?
It differs by sex and age. As a rough guide, many sources put a healthy range around 21 to 33 percent for women and 8 to 20 percent for men, since women naturally carry more essential fat. Very low body fat is not healthier and carries its own risks, so aim for a sensible range rather than the lowest number.
How does the Navy method measure body fat?
It estimates body fat from your height and a few tape measurements: neck and waist for everyone, plus hips for women. It is not as precise as a lab scan, but it is free, easy to repeat at home, and good at tracking change over time when you measure consistently.
Is body fat percentage better than BMI?
For many purposes, yes, because it distinguishes fat from muscle, bone and water, which BMI cannot. Two people at the same weight or BMI can have very different body compositions. That said, the Navy estimate is approximate, so use it as a trend tracker rather than an exact value.
How can I lower my body fat percentage?
Combine a modest calorie deficit with strength training and enough protein, so you lose fat while preserving muscle. Crash dieting tends to cost muscle and backfire. Measuring consistently and watching the trend over weeks is the best way to confirm you are losing fat rather than just weight.
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