Body fat calculator
Estimate your body fat percentage from tape measurements using the U.S. Navy circumference method, with your fat mass, lean mass and category.
Your body fat result
Body fat percentage
-%
Enter your measurements
- Essential
- Athletes and fitness
- Average
- Obese
- Category range
- -
- Fat mass
- -
- Lean mass
- -
Body fat categories
| Category | Men | Women |
|---|---|---|
| Essential fat | 2 to 5% | 10 to 13% |
| Athletes | 6 to 13% | 14 to 20% |
| Fitness | 14 to 17% | 21 to 24% |
| Average | 18 to 24% | 25 to 31% |
| Obese | 25% and above | 32% and above |
How it works
The U.S. Navy circumference method estimates the proportion of your body weight that is fat, using tape measurements of your neck and waist (and, for women, hips), plus your height. It does not require calipers or lab equipment, and is typically accurate to within about 3 to 4 percentage points of lab methods such as DEXA scanning.
- Choose sex and units
Women need one extra measurement: hip circumference.
- Measure neck and waist
Waist is measured level with the navel, not the narrowest point.
- Read your result
Body fat percentage, category, and fat and lean mass update as you type.
The Navy method formula
Men: 495 / (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450
Women: 495 / (1.29579 − 0.35004 × log10(waist + hip − neck) + 0.22100 × log10(height)) − 450
All measurements are in centimeters. A 70 in (177.8cm) man weighing 180 lb with a 15 in neck and 34 in waist comes out to 17.4% body fat, in the Fitness category.
How to reduce body fat
- Caloric deficit: eat fewer calories than you burn. A deficit of 500 calories a day leads to roughly 1 lb of fat loss a week.
- Strength training: building muscle raises your metabolism and improves body composition.
- Protein intake: aim for around 0.7 to 1g of protein per pound of body weight to preserve muscle while losing fat.
- Cardio: both interval and steady state cardio burn calories and improve cardiovascular health.
Measurement limitations
The Navy method typically runs 3 to 4 percentage points off lab methods like DEXA or hydrostatic weighing, and inconsistent tape placement adds further error. Measure at the same time of day, preferably in the morning, for consistent results. Dropping below essential fat levels is dangerous and can cause hormonal problems, so treat a very low result as a reason to check with a professional rather than a target.
Frequently asked questions
How does the Navy body fat calculator work?
The U.S. Navy method uses body circumference measurements to estimate body fat. For men it needs height, waist (at the navel) and neck. For women it also needs hip circumference. The formula applies logarithms to these measurements, does not use calipers, and needs no weight input for the percentage itself, which makes it accessible without special equipment.
What are healthy body fat ranges for men and women?
This calculator uses: for men, essential fat 2 to 5%, athletes 6 to 13%, fitness 14 to 17%, average 18 to 24%, obese 25% and above. For women, essential fat 10 to 13%, athletes 14 to 20%, fitness 21 to 24%, average 25 to 31%, obese 32% and above. Women have higher essential fat requirements due to hormonal and reproductive physiology.
How accurate is the Navy circumference method?
The Navy method is convenient but not highly precise, typically running 3 to 4 percentage points off lab grade methods such as DEXA scanning or hydrostatic (underwater) weighing. Measurement errors such as inconsistent tape placement can add further error. It is useful for tracking your own trend over time, but not for clinical decisions.
Where exactly do I measure my waist for this calculator?
Waist circumference here is measured at the navel, not at the narrowest point of your torso. That differs from the waist measurement used for waist to hip ratio, which uses the narrowest point. Using the wrong position will produce an inaccurate result, so keep your measurement location consistent between checks.
Is body fat percentage a better measure than BMI?
Body fat percentage directly measures how much of your weight is fat versus lean mass, which makes it more informative than BMI for body composition. The Navy method is still an estimate with 3 to 4 percentage points of error, though, so using both BMI and body fat together gives a more complete picture than either alone. See the BMI calculator for the other half of that picture.