Body Fat Percentage Calculator

HealthLast updated: August 17, 2026

Body fat percentage tells you what share of your total body weight is fat tissue. Unlike BMI, it separates muscle from fat: an athlete with a high muscle mass may look 'overweight' by BMI while being athletic by body fat percentage. That makes it a far more meaningful measure for tracking body composition.

This calculator uses the US Navy circumference method: with nothing but a tape measure you record your neck, waist, and (for women) hip circumference and get an estimate of your body fat percentage. The method needs no calipers or bioelectrical impedance device and gives a practical estimate within about 3-4 percentage points.

cm
cm
Measure just below the Adam's apple, without pulling the tape tight.
cm
Men should measure at navel level, women at the narrowest part of the waist.

Body Fat Percentage Reference Thresholds

Once your body fat percentage has been calculated with the US Navy circumference method, it is classified against the category thresholds below. The thresholds differ by sex; the essential fat percentage is physiologically higher in women.

Essential fat
Men: below 6% | Women: below 14%
The minimum fat needed for organ function; below this level there is a health risk
Athletic
Men: 6% – 13.9% | Women: 14% – 20.9%
The range seen in athletes who train regularly
Fitness
Men: 14% – 17.9% | Women: 21% – 24.9%
The typical range for healthy adults who stay physically active
Average
Men: 18% – 24.9% | Women: 25% – 31.9%
An acceptable range; metabolic risk rises as you approach the upper bound
Obese
Men: 25% and above | Women: 32% and above
The range in which the risk of cardiovascular and metabolic disease is markedly elevated
Margin of error of the method
±3% – 4%
Circumference measurement is an estimate; clinical methods such as DEXA or hydrostatic weighing give more precise results

ACE (American Council on Exercise) category thresholds; still the reference in common useKaynak: American Council on Exercise (ACE) body fat percentage categories — US Navy circumference method

US Navy circumference method

Men:   Body fat % = 495 / (1.0324 − 0.19077 × log₁₀(Waist − Neck) + 0.15456 × log₁₀(Height)) − 450
Women: Body fat % = 495 / (1.29579 − 0.35004 × log₁₀(Waist + Hip − Neck) + 0.221 × log₁₀(Height)) − 450

All measurements are in centimeters. The formula estimates body density from circumference measurements and converts it to a fat percentage with the Siri equation; compared with reference methods such as DEXA, it typically deviates by about 3-4 percentage points.

How to Calculate

  1. Measure your neck just below the Adam's apple, with the tape angled slightly downward at the front and not pulled tight.
  2. Measure your waist at navel level if you are male, or at the narrowest point of the waist if you are female, without sucking your stomach in.
  3. If you are female, measure your hips at their widest point, keeping the tape parallel to the floor.
  4. Enter the measurements in centimeters and read your body fat percentage and category immediately.
  5. For tracking, always repeat the measurement at the same time of day (ideally in the morning before eating) and in the same way.

Worked Examples

A man of average build

For a man 180 cm tall with a 38 cm neck and a 90 cm waist, the formula gives a body fat percentage of 19.8%, which falls in the 'Average' category for men (18% - 24.9%).

Body fat percentage: 19.8% · Category: Average

A woman of average build

For a woman 165 cm tall with a 33 cm neck, a 75 cm waist, and 95 cm hips, the body fat percentage comes to 26.9%, which is the 'Average' category for women (25% - 31.9%).

Body fat percentage: 26.9% · Category: Average

An athletic man

For a fit man 178 cm tall with a 40 cm neck and a 78 cm waist, the result is 8.8%, which falls in the 'Athletic' category (6% - 13.9%). A small waist-to-neck difference points to a low body fat percentage.

Body fat percentage: 8.8% · Category: Athletic

Frequently Asked Questions

How accurate is this method?
Compared with reference methods such as a DEXA scan, the US Navy circumference method lands within about 3-4 percentage points for most people. It is not a precision laboratory measurement, but as long as you take the measurements the same way every time, it is quite reliable for tracking change over time.
What is a healthy body fat percentage?
Under the ACE classification, roughly 6-24% for men and 14-31% for women can be considered healthy bands; the 'Fitness' zone is 14-17.9% for men and 21-24.9% for women. Women naturally carry a higher essential fat percentage than men because of hormonal and reproductive functions.
Why is a hip measurement needed for women?
In women, fat tissue is stored mainly around the hips and thighs, so the waist measurement alone does not represent body density well. The female version of the formula therefore uses waist + hip − neck, which improves the accuracy of the estimate.
When and how should I take the measurements?
For the most consistent results, measure in the morning before eating and before exercise. Keep the tape in contact with the skin but do not compress the tissue, and breathe out normally. Taking each measurement twice and using the average reduces small errors.
Can my body fat be high while my BMI is normal?
Yes; this is called 'normal weight obesity'. People with low muscle mass and a wide waist can have a normal BMI while carrying a high body fat percentage and metabolic risk. The reverse also happens: muscular athletes often have a high BMI but a low body fat percentage.
How can I lower my body fat percentage?
The core strategy is to create a calorie deficit while preserving muscle mass: a daily deficit of 300-500 kcal, resistance training 2-3 days a week, and adequate protein intake (roughly 1.6-2.2 g per kilogram) are recommended. Crash diets cost you muscle and lower body fat less than expected; a calorie needs calculator can help you set your target.