Body Fat Calculator
Estimate your body fat percentage quickly and accurately using the US Navy tape measurement method.
The US Navy Method Equation
This logical formula derives body density from circumference measurements and converts it to a body fat percentage. The formula differs slightly between men and women to account for biological differences.
495 / (1.0324 - 0.19077 * log10(waist - neck) + 0.15456 * log10(height)) - 450
WaistWaist circumference (cm)
NeckNeck circumference (cm)
HeightHeight (cm)
HipHip circumference (cm) - Women only
Manual Calculation Example (Male)
Example for a male with: Waist = 85 cm, Neck = 38 cm, Height = 175 cm.
1
Check Difference
Waist minus Neck
85 - 38 = 47
2
Logarithmic Calculation
Log base 10 of the difference
log10(47) ≈ 1.672
3
Height Log
Log base 10 of height
log10(175) ≈ 2.243
4
Apply Formula
Substitute values into equation
495 / (1.0324 - 0.19077(1.672) + 0.15456(2.243)) - 450
5
Result
Final estimated body fat percentage
~15.2%
Understanding Body Fat
Body fat percentage is a measure of fitness level, since it is the only body measurement which directly calculates a person's relative body composition without regard to height or weight.
General Body Fat Percentage Categories (ACE)
| Description | Women | Men |
|---|---|---|
| Essential Fat | 10-13% | 2-5% |
| Athletes | 14-20% | 6-13% |
| Fitness | 21-24% | 14-17% |
| Average | 25-31% | 18-24% |
| Obese | 32%+ | 25%+ |
Frequently Asked Questions
How accurate is the US Navy body fat calculator?
The US Navy method is reasonably accurate for most people, typically within 3-4% of more precise methods. It compares favorably to skinfold calipers but is less accurate than DEXA scans.
What is a healthy body fat percentage?
For men, 10-20% is considered fit/healthy, while 6-13% is athletic. For women, 18-28% is healthy and 14-20% is athletic. Essential fat minimums are 2-5% for men and 10-13% for women.
How do I measure my waist for body fat calculation?
Measure your waist at the narrowest point (usually at the navel for men, or between the lowest rib and hip bone for women). Keep the tape horizontal and snug but not tight.
Real-World Body Fat Scenarios
Scenario 1: Athletic Male
MeasurementMale, 30, 6'0"
Waist32 inches
Neck16 inches
Estimated Body Fat12%
CategoryFitness/Athlete
Navy Method Error±3%
✅ Success:At 12% body fat, muscle definition is clearly visible. This is a common target for recreational athletes.
Scenario 2: Healthy Female
MeasurementFemale, 28, 5'6"
Waist28 inches
Hips38 inches
Neck13.5 inches
Estimated Body Fat24%
CategoryHealthy/Fit
💡 Info:Women naturally carry more essential fat than men (minimum 10-13%). 24% is considered a very healthy range.
Scenario 3: Overweight Male (Weight Loss Target)
MeasurementMale, 45, 5'10"
Waist40 inches
Neck17 inches
Estimated Body Fat28%
CategoryOverweight
RecommendationTarget 20% or less
⚠️ Warning:Waist circumference over 40 inches for men increases risk for cardiovascular disease. Targeted fat loss is recommended.