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Body Fat Percentage Calculator

Estimate your body fat percentage with nothing but a tape measure, using the U.S. Navy method, the most validated no-equipment estimate there is.

Calculate Your Body Fat %

Please enter valid measurements. Waist must be larger than neck.
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Estimated Body Fat %
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How the Navy Method Actually Works

Without calipers, a DEXA scan or a bioimpedance scale, a tape measure is the only realistic input available, and the U.S. Navy method is the best-validated formula built around one. It was developed for military fitness standards and has been checked against more accurate lab methods for decades. It will not replace a real scan, but for a free, at-home estimate, it is the honest ceiling of what a tape measure can tell you.

Men
%BF = 495 ÷ (1.0324 - 0.19077 × log10(waist - neck) + 0.15456 × log10(height)) - 450

Women
%BF = 495 ÷ (1.29579 - 0.35004 × log10(waist + hip - neck) + 0.22100 × log10(height)) - 450

Categories (men / women)
Essential fat: 2-5% / 10-13% · Athletes: 6-13% / 14-20% · Fitness: 14-17% / 21-24% · Average: 18-24% / 25-31% · Obese: 25%+ / 32%+

The single biggest source of error here is not the formula, it is measurement technique. Measure waist at the navel, neck just below the larynx, and hip at the widest point, keeping the tape level and snug but not compressing the skin. Two measurements taken five minutes apart, by two different people, can easily disagree by more than the formula's own margin of error.

The SanoobFit Position

The scale tells you almost nothing useful on its own. Two people at the same weight can have completely different bodies, and only one of them might actually need to change anything. Body composition, not bodyweight, is the number worth tracking over months.

Where This Fits in APEX

Inside SanoobFit's APEX system, real body composition is tracked as the Body Composition standard, not bodyweight alone. It is part of the Stage 1, Foundation, profile that every Fat Loss program is built around.

Standard: Body Composition Stage 1: Foundation Program: Fat Loss

One Estimate Is a Starting Point, Not a Tracker

The SanoobFit app tracks your real training and body composition over time, not just a single number, free to start.

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Frequently asked questions

How accurate is the Navy method body fat calculator?
The Navy method is typically within about 3 to 4 percent body fat of a DEXA scan for most body types, which makes it one of the better free, no-equipment estimates available. It gets less accurate at the extremes of leanness or size, and measurement technique matters as much as the formula itself.
Why does the Navy method need my neck measurement?
Neck circumference correlates with upper-body fat distribution. Combined with waist (and hip for women), it lets the formula estimate body fat without calipers or a scan.
Why is my smart scale's body fat number different from this calculator?
Bioimpedance scales estimate body fat by sending a small electrical current through your body, which is highly sensitive to hydration, recent food, and time of day. A 5 to 8 percent difference between two different methods is normal, not a sign either one is wrong.

Related Reading

This tool gives an estimate to guide your plan. It is not a diagnosis and does not replace a real body composition scan or advice from your own doctor.