How to use the Body Fat calculator
- Enter your numbers. Fill in sex, units, height, weight, neck circumference, waist.
- Read your results. Results update instantly. The headline shows the estimated body fat; the breakdown and table below show the details.
How the Navy method works
The U.S. Navy circumference method estimates body fat from height and a few tape measurements. It’s typically within a few percentage points of lab methods like DEXA for most people.
The formula (inches)
Women: %BF = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387
How to measure
- Neck: just below the larynx, tape sloping slightly down to the front.
- Waist: men at the navel; women at the narrowest point.
- Hips (women): at the widest point of the buttocks.
Worked example
With these inputs: sexMale; unitsInches; height70; weight (lb or kg)180; neck circumference15.5; waist (at navel)35.
The calculator gives a estimated body fat of 18.5% (average). Other results: categoryAverage, fat mass33.3 lb, lean mass146.7 lb, methodU.S. Navy.
What your results mean
The result estimates the share of your weight that is fat, from body measurements. Tape-measure methods are typically within a few percentage points of lab methods, so focus on the trend over time.
Tips
- Measure in the morning, relaxed, with the tape snug but not compressing skin.
- Take each measurement twice and average them.
- Re-measure every 4–8 weeks rather than daily.
Frequently asked questions
What is a healthy body fat percentage?
Ranges vary by source, age and sex; American Council on Exercise guidelines list about 14–24% for men and 21–31% for women as “fitness” to “acceptable.”
How accurate is the Navy body fat method?
It is a reasonable estimate for most people, but DEXA or hydrostatic weighing is more precise.
How accurate is it?
Usually within 3–4 percentage points, depending on measurement technique.
What is a healthy body fat percentage?
ACE ranges: about 14–24% for fit-to-average men and 21–31% for women. Essential fat is 2–5% for men and 10–13% for women.
Why does it ask for hips only for women?
The Navy formula for women includes hip circumference; the men’s formula doesn’t.
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