body composition
Body fat percentage calculator
What is body fat percentage?
Body fat percentage is the proportion of your total body weight that is fat mass. It is a more useful fitness metric than BMI because it distinguishes between fat and muscle. A lean, muscular person may have a "overweight" BMI but a healthy body fat percentage.
How to use this calculator
- Select your sex and enter your measurements in centimetres (or inches).
- Men need: neck circumference and waist circumference at the navel.
- Women need: neck, waist (at navel), and hip (at widest point) circumferences.
- Click Calculate Body Fat to see both the Navy and BMI-based estimates.
The formulas
US Navy formula (primary)
Male: 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76
Female: 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387
All measurements in cm.
BMI-based Deurenberg formula (secondary)
Body fat % = 1.20 × BMI + 0.23 × age − 10.8 × sex − 5.4
(sex: male = 1, female = 0)
How to interpret your result
The Navy formula is generally more accurate than the BMI method for fit individuals. Both are estimates — DEXA scans are the gold standard. Use trends over time rather than a single reading.
Related tools
- Lean Body Mass Calculator — calculate your fat-free mass
- TDEE Calculator — use body composition to refine your calorie target
Read more
What is body fat percentage?
Body fat percentage is the proportion of your total body weight that is fat mass. It is a more useful fitness metric than BMI because it distinguishes between fat and muscle. A lean, muscular person may have a "overweight" BMI but a healthy body fat percentage.
How to use this calculator
- Select your sex and enter your measurements in centimetres (or inches).
- Men need: neck circumference and waist circumference at the navel.
- Women need: neck, waist (at navel), and hip (at widest point) circumferences.
- Click Calculate Body Fat to see both the Navy and BMI-based estimates.
The formulas
US Navy formula (primary)
Male: 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76
Female: 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387
All measurements in cm.
BMI-based Deurenberg formula (secondary)
Body fat % = 1.20 × BMI + 0.23 × age − 10.8 × sex − 5.4
(sex: male = 1, female = 0)
How to interpret your result
The Navy formula is generally more accurate than the BMI method for fit individuals. Both are estimates — DEXA scans are the gold standard. Use trends over time rather than a single reading.
Related tools
- Lean Body Mass Calculator — calculate your fat-free mass
- TDEE Calculator — use body composition to refine your calorie target
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