Body Fat Calculator
Calculate your body fat percentage, lean mass, and fat mass using the U.S. Navy method. Enter your measurements below to get accurate results.
Body Fat Percentage
Body Fat Categories
What is a Body Fat Calculator?
A Body Fat Calculator is a health assessment tool designed to estimate the percentage of your total body weight that consists of adipose tissue (fat) versus lean mass (muscle, bone, and water). Unlike BMI, which only looks at height and weight, a Body Fat Calculator typically uses the U.S. Navy Method, incorporating tape measurements of the waist, neck, and hips to provide a more accurate picture of body composition.
At Nexli Calculator, our tool is essential for anyone on a fitness journey. Whether you are trying to reveal six-pack abs, bulk up for sports, or simply reduce health risks, knowing your body fat percentage is a far better metric of progress than the number on a standard scale.
Why Use Our Body Fat Calculator?
True Health Metric
Distinguish between being "heavy" due to muscle versus being overweight due to fat. BMI often mislabels muscular people.
U.S. Navy Standard
We use the widely accepted U.S. Navy tape measure formula, which offers high accuracy without the need for expensive DEXA scans.
Track Recomposition
Perfect for "Body Recomposition" (losing fat while gaining muscle), where your weight might stay the same but your fat % drops.
Completely Free
Nexli Calculator offers this advanced fitness utility 100% free with no registration required.
Body Fat Formulas & Logic
We utilize the U.S. Navy Method, which relies on logarithmic equations based on body circumference. The logic differs biologically for men and women:
Formula for Men
Based on abdominal and neck measurements.
- 495 / (1.0324 - 0.19077(log10(Waist - Neck)) + 0.15456(log10(Height))) - 450
- *Measurements must be precise for accuracy. Men accumulate fat differently than women (visceral vs subcutaneous).
Formula for Women
Includes hip measurement.
- 495 / (1.29579 - 0.35004(log10(Waist + Hip - Neck)) + 0.22100(log10(Height))) - 450
- *Women naturally carry more essential fat in the hip area for reproductive health.
How to Use Our Body Fat Calculator
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1
Select Gender
Choose Male or Female (this is crucial as fat distribution patterns differ greatly).
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2
Measure Circumferences
Using a soft tape measure, record your Height, Neck, Waist (at the navel), and Hips (for women only).
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3
Calculate
Click the button to see your Body Fat Percentage, Fat Mass (in lbs/kg), and Lean Mass.
Frequently Asked Questions (FAQ)
What is the difference between BMI and Body Fat Percentage? ▼
What is a "Healthy" Body Fat percentage? ▼
For Women: 21-24% is fit, 25-31% is average.
Women naturally require higher essential fat levels for hormonal balance and reproductive health.