Body Fat Percentage Calculator
Estimate your body fat percentage using the U.S. Navy circumference method. Enter waist, neck, and hip measurements to get a quick, tape-measure-based body composition reading without calipers or lab equipment.
About this calculator
The U.S. Navy body fat method estimates body composition from simple circumference measurements rather than underwater weighing or DEXA scans. For males, the formula is: BF% = 495 / (1.0324 − 0.19077 × log₁₀(waist − neck) + 0.15456 × log₁₀(height)) − 450. For females, hip circumference is added: BF% = 495 / (1.29579 − 0.35004 × log₁₀(waist + hip − neck) + 0.22100 × log₁₀(height)) − 450. The logarithmic terms compress the wide range of circumference values into a workable scale. This method correlates well with hydrostatic weighing for most body types, though it can slightly overestimate fat in very muscular individuals. All measurements should be taken in inches at the specified anatomical landmarks for accurate results.
How to use
Suppose a male is 70 inches tall, with a 34-inch waist and 15-inch neck. Step 1: Compute waist − neck = 34 − 15 = 19. Step 2: log₁₀(19) ≈ 1.2788; log₁₀(70) ≈ 1.8451. Step 3: Denominator = 1.0324 − 0.19077 × 1.2788 + 0.15456 × 1.8451 = 1.0324 − 0.2440 + 0.2852 = 1.0736. Step 4: BF% = 495 / 1.0736 − 450 ≈ 461.0 − 450 = 11.0%. This man's estimated body fat is approximately 11%, which falls in the fitness category for adult males.
Frequently asked questions
How accurate is the Navy method body fat calculator compared to DEXA or hydrostatic weighing?
The Navy method typically falls within 3–4 percentage points of DEXA scanning for average body types, making it a reliable field estimate. It tends to be less accurate for very muscular athletes, where it may overestimate fat, and for extremely obese individuals. Because it requires only a tape measure, it is widely used by the U.S. military for large-scale screening. For clinical or competitive purposes, DEXA or hydrostatic weighing remains the gold standard.
Where exactly should I measure waist and neck circumference for the body fat formula?
Measure the waist at the narrowest point, typically just above the navel and below the ribcage, while relaxed and exhaling normally. The neck should be measured just below the larynx (Adam's apple) on a slight downward slope. For females, the hip measurement is taken at the widest point around the buttocks. Consistent measurement technique matters more than perfection — always measure at the same time of day and in the same posture to track changes reliably.
What is a healthy body fat percentage range for men and women?
For men, essential fat is roughly 2–5%, athletes fall between 6–13%, fitness levels are 14–17%, acceptable is 18–24%, and above 25% is considered obese. For women, essential fat is 10–13%, athletes 14–20%, fitness 21–24%, acceptable 25–31%, and above 32% is obese. These ranges vary slightly by source and age group. Older adults naturally carry more fat than younger adults at the same fitness level, so age-adjusted charts provide a more nuanced picture.