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Body Fat Calculator
Calculate your body fat percentage using the US Navy Method. More accurate than BMI for athletes and bodybuilders. Updated for 2025.
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Understanding Body Fat Percentage
What is Body Fat Percentage?
Body fat percentage is the total mass of fat divided by total body mass, multiplied by 100. It includes essential body fat and storage body fat. Essential body fat is necessary to maintain life and reproductive functions.
The US Navy Method
This calculator uses the US Navy Method, which is widely considered one of the most accurate ways to estimate body fat percentage without specialized equipment like hydrostatic weighing or DEXA scans. It uses body circumference measurements to estimate body density.
Body Fat Categories (ACE Standards)
| 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%+ |
💡 Expert Tip from Sarah Jenkins, RD
Most people obsess over the scale, but body fat percentage tells the real story. I've worked with clients who "gained weight" but dropped 2 dress sizes because they built muscle and lost fat. The Navy Method is about 3-4% accurate compared to a DEXA scan—good enough for tracking progress without spending $100+ per test.
⚠️ Common Mistake: Measuring at the Wrong Spot
Waist measurement is NOT at your belly button—it's at the narrowest point, usually an inch or two above. Hip measurement (for women) is at the widest part of your buttocks. Measure in the morning before eating, and don't suck in—you're only lying to yourself!
Body Fat vs BMI: Which Is Better?
BMI doesn't distinguish between fat and muscle. A bodybuilder with 8% body fat can be classified as "overweight" by BMI. Body fat percentage is far more accurate for assessing health risks, especially for athletes and people who strength train regularly.
Why Track Body Fat?
Tracking body fat percentage is often more useful than just tracking weight. You might lose weight but lose muscle mass, which isn't ideal. Or you might gain weight while building muscle and losing fat. Body fat percentage gives you a better picture of your actual body composition.
References
- Hodgdon, J.A. and Beckett, M.B. (1984). Prediction of percent body fat for U.S. Navy men and women.
- American Council on Exercise. Body Fat Percentage Norms.
Reviewed by Sarah Jenkins, RD
Registered Dietitian & Sports Nutritionist
Sarah helps athletes understand their body composition and improve their performance through smart nutrition.
Frequently Asked Questions
How accurate is the Navy Method?
It's about 3-4% accurate compared to a DEXA scan. Not perfect, but good enough for tracking progress without spending $100+ per test. Way better than BMI for athletes.
What's a healthy body fat percentage?
For men: 14-24% is generally healthy. For women: 21-31%. Athletes are lower (6-13% men, 14-20% women). Going too low is dangerous—you need essential fat for hormone production and organ protection.
Should I measure in the morning or evening?
Morning, before eating or drinking. Your measurements can vary by inches throughout the day due to water retention and food. For consistency, same time, same conditions every time you measure.