Body Fat Calculator
Calculate body fat percentage using the US Navy method and check your body fat category.
Input Information
Result
Accurately measure body fat percentage with the US Navy method!
This body fat calculator uses the US Navy method to estimate your body fat ratio. By measuring height, weight, neck circumference, and waist circumference (plus hip for females), it scientifically calculates body fat percentage.
Body fat percentage is a more accurate body composition indicator than BMI, useful for understanding the muscle-to-fat ratio. Two people with the same BMI can have very different health statuses depending on muscle vs. fat, making body fat measurement important.
Results are classified as Essential Fat, Athletes, Fitness, Acceptable, or Obese, and are used for planning personalized diet and exercise programs.
Term Glossary
- Body Fat Percentage
- The ratio of fat to total body weight. An important health indicator showing the fat-muscle ratio that weight alone cannot reveal.
- US Navy Method
- A body fat estimation formula developed by the US Navy using height and body measurements (neck, waist, hip). Allows reasonably accurate estimation without calipers.
- Lean Mass
- Weight minus fat: muscles, bones, organs, etc. Directly affects BMR and is a key indicator for healthy weight management.
- Select sex → Choose Male or Female
- Enter measurements → Enter neck and waist circumference in cm (females also enter hip)
- Calculate → Click the Calculate button
- View results → Check body fat percentage (%) and body fat classification (Normal~Obese)
Male, Neck 38cm, Waist 90cm
Body fat ≈ 495 / (1.0324 - 0.19077×log10(90-38) + 0.15456×log10(170)) - 450 ≈ ~22% → Normal range
Female, Neck 34cm, Waist 75cm, Hip 98cm
Body fat ≈ 495 / (1.29579 - 0.35004×log10(75+98-34) + 0.22100×log10(160)) - 450 ≈ ~30% → Mildly Obese
US Navy Body Fat Formula
Male Formula
BF% = 495 / (1.0324 - 0.19077 × log10(waist - neck) + 0.15456 × log10(height)) - 450Uses the difference between waist and neck to estimate relative fat distribution.
Female Formula
BF% = 495 / (1.29579 - 0.35004 × log10(waist + hip - neck) + 0.22100 × log10(height)) - 450Includes hip circumference to reflect fat distribution around the pelvis.
Body Fat Classification
Male
- Below 6%: Essential Fat
- 6-14%: Athletes
- 14-18%: Fitness
- 18-25%: Acceptable
- 25%+: Obese
Female
- Below 14%: Essential Fat
- 14-21%: Athletes
- 21-25%: Fitness
- 25-32%: Acceptable
- 32%+: Obese
Key tips for body fat measurement
1. Measure in the morning on an empty stomach
For the most accurate results, measure before eating or drinking. Measure after showering in light clothing.
2. Keep the tape horizontal
When measuring neck, waist, and hip, keep the tape level with the floor and wrap it naturally without pulling too tight.
3. Measure waist at the correct position
Males: midpoint between the lowest rib and iliac crest. Females: at the narrowest part (natural waistline).
4. Track trends regularly
Trends matter more than absolute values. Measure every 2-4 weeks to verify the effectiveness of your diet and exercise.
5. Don't rely on body fat alone
Use body fat percentage as a reference alongside BMI, and consider waist circumference, blood tests, and overall body composition.
QIs the US Navy method more accurate than other body fat measurements?
Compared to DEXA (~1.5% error), US Navy has ~3-4% error. Practical for home use but less accurate than clinical methods.
QWhat are the body fat percentage ranges?
Men: Essential 2-5%, Athletes 6-13%, Fitness 14-17%, Average 18-24%, Obese 25%+. Women: Essential 10-13%, Athletes 14-20%, Fitness 21-24%, Average 25-31%, Obese 32%+.
QIs the measurement inaccurate for very muscular individuals?
Yes. Very muscular individuals may have higher neck/waist measurements, potentially overestimating body fat. Skin-fold or DEXA is more reliable for athletes.
QWhat are the differences by age and sex?
Women naturally have higher essential fat (10-13% vs 2-5% for men). Body fat increases with age due to hormonal changes and decreased muscle mass.
QWhat changes can regular measurements reveal?
Tracking weekly/biweekly shows trends more accurately than single measurements. Consistency in measurement conditions (morning, fasted) improves comparability.