Body Fat Calculator
The US Navy method estimates body fat from a tape measure alone: it compares the circumference of the places you store fat against your height. Enter your measurements below to see your percentage, how your body weight splits into fat and lean mass, and where the figure falls against the standard fitness ranges.
- Accurate
- Real-time
- Easy to use
- 100% free
Body fat
21.7%
Waist-to-height ratio
0.52
Details
Updates as you typeThe Navy method uses a different equation for each.
Measure just below the larynx, tape sloping slightly down at the front.
Men measure at the navel; women measure at the narrowest point.
Used by the female equation only — measure at the widest point.
Used only to split the percentage into fat mass and lean mass.
Summary
Average — 18% to 25%Body fat
21.7%
Body weight
80.0 kg
- Fat mass17.3 kg22%
- Lean mass62.7 kg78%
- Lean mass share
- 78.3%
- Waist-to-height ratio
- 0.52
- Waist − neck
- 54.0 cm
- The Navy tape method estimates body fat to within about 3–4 percentage points of a DEXA scan. Measure at the same time of day, on bare skin, with the tape snug but not compressing.
- The bands shown are the male reference ranges.
How this is calculated
- Height
- 70.08 in
- Neck
- 14.96 in
- Waist
- 36.22 in
- Waist − neck
- 21.26 in
- log₁₀ of that circumference
- 1.3276
- log₁₀ of height
- 1.8456
- Body fat
- 21.7%
- Body weight
- 80.0 kg
- Fat mass = weight × body fat
- 17.3 kg
- Lean mass = weight − fat mass
- 62.7 kg
Compare scenarios
See how one change moves the result
- CurrentYour inputs as they stand21.7%Current
- Heightcm 222.514.9%
- Neck circumferencecm 47.514.4%
- Waist circumferencecm 11534.9%
For informational purposes only. This is not medical advice — consult a healthcare professional about your health.
Frequently asked questions
How accurate is the US Navy body fat method?
It typically lands within 3 to 4 percentage points of a DEXA scan, which is good enough to track a trend but not precise enough to chase a single number. Its strength is repeatability: measure the same way each time and the direction of change is reliable even if the absolute figure is off.
Why are the ranges different for men and women?
Women carry more essential fat — roughly 10 to 13 percent of body mass versus 2 to 5 percent for men — because of reproductive and hormonal tissue. A healthy female reading therefore sits about 8 to 10 percentage points above the male figure, so 25 percent is average for a woman but high for a man.
Where exactly should I measure my waist and neck?
Measure the neck just below the larynx with the tape sloping slightly downward at the front. Men measure the waist horizontally at the navel; women measure at the narrowest point of the torso, and the hips at the widest point of the buttocks. Keep the tape snug without compressing the skin.
Why does the calculator need my height?
Circumference alone cannot tell a large frame from a fat one. Height acts as the scaling term in the equation, so a 90cm waist reads very differently on someone 160cm tall than on someone 195cm tall. It is why two people with identical waists can get results ten points apart.
Why does it ask for my weight if the equation does not use it?
It does not affect the percentage at all — the Navy equation runs on circumferences and height alone. Weight is used only afterwards, to turn the percentage into two figures you can act on: how many kilograms of you are fat and how many are everything else. Lean mass is the number worth protecting during a diet.
Is body fat percentage better than BMI?
For an individual, usually yes, because it separates fat from muscle where BMI cannot — a muscular athlete can read obese on BMI and athletic here. BMI remains useful as a fast population-level screen and needs only a scale and a wall.