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Free Body Fat Percentage Calculator

A free body fat calculator estimates your body fat percentage using the U.S. Navy method. Pick your gender, enter your height, neck, and waist (plus hip for women) in cm or inches, and get an instant estimate with a category label and color-coded gauge — no signup, runs in your browser.

Estimate your body fat percentage with the U.S. Navy circumference method — the same tape-measure approach used by the military. Choose male or female, switch between centimeters and inches, and enter your height, neck, and waist (women also add hip). The tool applies the Navy formula and shows your result with an ACE category label (Essential Fat, Athletic, Fitness, Average, or Obese) and a color-coded gauge marking where you fall. It is an estimate, not a clinical measurement. Free, no signup, all math runs locally in your browser.

Gender
Units

Enter your measurements above to estimate your body fat percentage.

This is an estimate based on the U.S. Navy circumference method. It is not a substitute for clinical measurements such as DEXA scans, hydrostatic weighing, or skinfold calipers. Consult a healthcare professional for precise body composition assessment.

Runs 100% in your browser. Your data never leaves your device.

Implements the U.S. Navy body fat formula in plain JavaScript. Measurements are converted to centimeters and run through the Navy log-based equation, then matched to American Council on Exercise (ACE) category ranges. All calculations run locally in your browser with no external libraries or server calls.

How to Use Body Fat Percentage Calculator

  1. Select your gender — the formula and category ranges differ for men and women
  2. Choose centimeters or inches with the units toggle
  3. Enter your height, neck, and waist measurements (women also enter hip)
  4. Your estimated body fat percentage, category, and gauge update instantly

When Would You Use This?

Anyone tracking a cut or bulk uses this for a quick, repeatable body fat estimate between gym check-ins — a tape measure is far cheaper and more accessible than a DEXA scan.

The U.S. Navy method only needs height, neck, and waist (plus hip for women), so it is easy to redo weekly with consistent measurements to watch a trend rather than a single number.

Keep in mind this is an estimate. Circumference formulas can be off by several percent for very lean or very muscular bodies — treat it as a directional figure alongside how you look, lift, and feel, not a clinical result.

Frequently Asked Questions

Is this body fat calculator free to use?
Yes, completely free. No signup, no login, no payment ever.
Do I need to create an account?
No account needed. Open the tool, enter your measurements, and see your estimate immediately.
Is my data safe?
Everything runs in your browser. Your measurements are never uploaded to our servers.
How accurate is the U.S. Navy body fat method?
It is a reasonable estimate for most people and tracks changes well over time, but it can be off by several percent compared to DEXA scans or hydrostatic weighing, especially for very lean or very muscular individuals. Use it as a guide, not a clinical measurement.
How should I measure for the best result?
Measure with a flexible tape on bare skin, keeping it snug but not compressing. Measure neck below the larynx, waist at the navel for men, and the narrowest point for women, with hip at the widest point. Stay relaxed and breathe normally.
Why do men and women use different formulas?
Body fat distribution differs between sexes, so the Navy method uses separate equations and category ranges. Women add a hip measurement because fat patterning around the hips improves the estimate.

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