Body Fat Calculator

Free body fat calculator: estimate your body fat percentage using US Navy circumference measurements. Track your fitness progress with measurements for men and women.

Body fat percentage is the proportion of your total weight that comes from fat. It is a better indicator of fitness than BMI alone because it distinguishes between muscle and fat. This calculator uses the US Navy circumference method, which is based on height and body measurements.

Gender

Height (cm)

Body fat uses the US Navy formula — weight is not needed.

Neck (cm)

Waist (cm)

Body Fat

23.50%

Body Fat Percentage is a better health indicator than BMI alone.

Body Fat Reference Ranges:
Essential fat: 2-5% (men) / 10-13% (women)
Athletic: 6-13% (men) / 14-20% (women)
Fitness: 14-17% (men) / 21-24% (women)
Average: 18-24% (men) / 25-31% (women)
Obese: 25%+ (men) / 32%+ (women)

This calculator uses the US Navy circumference method based on height, neck, waist, and hip measurements.

Example

**Example: Body Fat Estimation**

A 30-year-old man, 175cm, neck 38cm, waist 85cm:

Body Fat % = 86.01 × log10(85 − 38) − 70.041 × log10(175) + 36.76
= **~16%**

Athletic range: 6-13% | Fit: 14-17% | Average: 18-24%

BMR uses the Mifflin-St Jeor formula. Body fat uses the US Navy circumference method. Ideal weight uses the Devine formula. These are estimates — consult a healthcare professional for personalized advice.

Frequently Asked Questions

What is the most accurate way to measure body fat?

DEXA scans, hydrostatic weighing, and BodPod are the most accurate methods. The US Navy circumference method used here provides a reasonable estimate within 3-4% of these lab methods.

What BMR formula does this calculator use?

We use the Mifflin-St Jeor equation, which is considered the most accurate for the general population. For men: 10xweight(kg) + 6.25xheight(cm) - 5xage(y) + 5. For women: 10xweight + 6.25xheight - 5xage - 161.

What is a healthy BMI range?

A BMI between 18.5 and 24.9 is considered healthy. Below 18.5 is underweight, 25-29.9 is overweight, and 30+ is obese. BMI is a screening tool - it doesn't account for muscle mass or body composition.

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