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Body Fat Calculator (US Navy Method)

Estimate body fat percentage with the US Navy method and get daily protein, carb, and fat macro targets.

Results update instantly.Change any value and the estimate recalculates on the spot.

Health

Body fat & macros

Estimate body fat with the US Navy method and get daily macro targets.

in
in
in
lb
%
%
%

Body fat percentage

-

  • Fat mass-
  • Lean mass-
  • Protein target-
  • Carb target-
  • Fat target-

The Navy method is an estimate - DEXA scanning is the reference standard. Macro targets are a starting split, not medical advice. Discuss nutrition plans with a qualified clinician.

How to use this calculator

1. Enter sex, height, and tape measurements in inches. 2. Add your weight and a daily calorie target. 3. Adjust the protein, carb, and fat shares and read the gram targets.

Worked example

Male, 70 in tall, 16 in neck, 34 in waist, 180 lb, 2,000 calories at 30/40/30: body fat about 15.5%, fat mass about 27.9 lb, lean mass about 152.1 lb, with targets of 150 g protein, 200 g carbs, and 67 g fat.

How the math works

The US Navy formula estimates body fat from the relationship between waist, neck, and height (plus hips for women) using logarithms fitted to underwater-weighing data. Macro grams come from the calorie shares: protein and carbs provide 4 calories per gram, fat provides 9.

How accurate is the Navy method?
Usually within 3 to 4 percentage points of DEXA for most people. It struggles with very muscular or very lean bodies, where the tape cannot tell muscle from fat.
Where exactly do I measure?
Waist at the navel, relaxed. Neck just below the Adam's apple. Hips at the widest point. Keep the tape snug but not compressing the skin, and measure in the morning for consistency.
What is a healthy body fat range?
Rough guides: men 10-20%, women 18-28% for general fitness. Athletes run lower. These are population ranges, not personal prescriptions.
Should the macro shares add to 100%?
Yes, for the gram targets to match your calorie target. If they do not add to 100%, the grams still reflect the shares you entered against the calorie total.

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How it works

How the Body Fat Calculator (US Navy Method) works

Quick answer: The US Navy method estimates body fat from height, neck, and waist (plus hips for women). A man who is 70 in tall with a 16 in neck and 34 in waist is about 15.5% body fat. On 2,000 kcal with a 30/40/30 split, his macro targets are 150 g protein, 200 g carbs, and 67 g fat.

Formula

Men: 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76
Women: 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387

Measurements are in inches. Macro targets use 4 kcal per gram for protein and carbs and 9 kcal per gram for fat.

Worked example

Male, 70 in, neck 16 in, waist 34 in, 180 lb: 15.5% body fat, 27.9 lb fat mass, 152.1 lb lean mass.

Male, 70 in tall, 16 in neck

WaistBody fat
30 in6.1%Open
32 in11.1%Open
34 in15.5%Open
36 in19.4%Open
38 in23.0%Open
40 in26.2%Open

Assumptions and limits

  • Tape-measure methods are typically within a few percentage points of lab methods, with more error at the extremes.
  • An estimate for general information, not a medical assessment.

Frequently asked questions

How accurate is the Navy method?

Usually within 3 to 4 percentage points of DEXA for most people. It struggles with very muscular or very lean bodies, where the tape cannot tell muscle from fat.

Where exactly do I measure?

Waist at the navel, relaxed. Neck just below the Adam's apple. Hips at the widest point. Keep the tape snug but not compressing the skin, and measure in the morning for consistency.

What is a healthy body fat range?

Rough guides: men 10-20%, women 18-28% for general fitness. Athletes run lower. These are population ranges, not personal prescriptions.

Should the macro shares add to 100%?

Yes, for the gram targets to match your calorie target. If they do not add to 100%, the grams still reflect the shares you entered against the calorie total.

Where do I measure my waist?

For men, at the navel. For women, at the narrowest point. Measure the neck just below the larynx.

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