Body fat calculator

Estimate your body fat percentage using the U.S. Navy method. All you need is a tape measure.

Body fat calculator inputs

cm
kg
cm
cm
Body fat
18.5%
Fitness
Fat mass
13.9 kg
Lean mass
61.1 kg

Body fat categories

CategoryMenWomen
Essential fat2–5%10–13%
Athletes6–13%14–20%
Fitness14–17%21–24%
Average18–24%25–31%
Obese25%+32%+

U.S. Navy body fat formula

Male: BF% = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76
Female: BF% = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387

Measurements in centimetres. Waist is measured at the navel, neck at the narrowest point, and hips at the widest point (women only).

How to measure correctly

  • Neck: Measure at the narrowest point, just below the larynx (Adam's apple). Keep the tape level.
  • Waist: Measure at the navel level while standing. Don't suck in your stomach.
  • Hips (women): Measure at the widest point of the buttocks/hips while standing with feet together.
  • Use a flexible tape measure and keep it snug but not compressing the skin.

Frequently asked questions

Why is body fat percentage better than BMI?

BMI doesn't distinguish between muscle and fat. A muscular person can have a high BMI but low body fat. Body fat percentage directly measures your fat-to-lean mass ratio, giving a more accurate picture of body composition.

How can I reduce body fat?

Create a moderate calorie deficit (300-500 cal/day), prioritise protein intake (1.6-2.2g per kg bodyweight), do resistance training 2-4 times per week, and get adequate sleep. Losing 0.5-1% body fat per month is a sustainable rate.

What is the most accurate body fat measurement method?

DEXA scan is the gold standard (±1-2% accuracy). Hydrostatic weighing and Bod Pod are also very accurate. The U.S. Navy method (±3-4%) is the best accessible option requiring no equipment beyond a tape measure.

Related calculators