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Health & Fitness · Guide

Body Fat Calculator Guide: The U.S. Navy Method Explained

Your weight alone cannot tell you whether you are carrying too much fat, because it mixes fat, muscle, bone and water into one number. Body fat percentage separates them: it is the share of your total mass made of fat. Estimating it with a tape measure — the U.S. Navy method — is free, fast and good enough for tracking trends between measurements.

In this guide

How the Navy method works

The method uses two circumference measurements: the waist (at the navel) and, for men, the neck. For women it also measures the hips. Combined with height, these go into a standard equation that estimates the percentage of your mass that is fat.

What the ranges mean

For men, roughly 10–20% is considered lean and 20–25% average, with obesity starting around 25%+. For women, 20–30% is lean to average, with higher percentages carrying more health risk. Athletic ranges sit below these — but extremely low levels are not healthier for most people.

Measuring for accuracy

Take measurements in the morning, before meals, and with the tape level and snug but not compressing the skin. Because the estimate varies with hydration and technique, measure consistently — same time, same method — and judge changes over weeks rather than single days.

Key takeaways

  • Body fat % separates fat from muscle and bone.
  • The Navy method uses waist, neck and hip tape measures.
  • Healthy ranges differ meaningfully by sex.
  • Track trends with consistent measurements, not single days.

Frequently asked questions

How accurate is the Navy body fat method?

It is a solid estimate, typically within a few percentage points of lab methods for most people, and very good at tracking changes over time.

What is a healthy body fat percentage?

For men, roughly 10–20%; for women, roughly 20–30%. Levels within these bands are associated with the lowest health risks for the general population.

Can two people at the same weight have different body fat?

Absolutely. Body composition varies widely — an athlete can weigh the same as someone with much more fat but carry far more muscle and far less fat.

Put these numbers to work

BMI, BMR, daily calories, ideal weight and body fat — instantly.

Body Fat Calculator

Estimate body fat percentage with the U.S. Navy method.

BMI Calculator

Calculate your Body Mass Index and healthy weight range.

BMR Calculator

Calculate your Basal Metabolic Rate with the Mifflin-St Jeor equation.

Ideal Weight Calculator

Find your ideal weight range using four medical formulas.

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