Body Fat Percentage Calculator (U.S. Navy Method)
Measure your waist, neck (and hips for women) with a tape and get a body fat estimate — no scale, no calipers.
Body fat percentage chart: women and men
| Category (ACE) | Women | Men |
|---|---|---|
| essential fat | 10 – 13% | 2 – 5% |
| athletes | 14 – 20% | 6 – 13% |
| fitness | 21 – 24% | 14 – 17% |
| average | 25 – 31% | 18 – 24% |
| above average | 32%+ | 25%+ |
Women need more essential fat for hormones and reproduction, which is why every band is higher. Body fat also tends to rise gradually with age at the same weight.
How to measure body fat at home
Use a soft tape, measure in the morning, tape snug but not tight. Waist: at the navel (men) or narrowest point (women). Neck: just below the larynx, tape sloping slightly down at the front. Hips (women): widest point. Enter the numbers with your height; the calculator applies the U.S. Navy circumference equations.
Navy vs Army method
Both use tape measurements. The Navy formula uses neck, waist and (for women) hips; the Army standard measures waist only, at the navel, and reads it against height and sex. The Navy method is the one used here because it is the better-validated of the two for the general public. Expect an error of about ±3–4 percentage points versus a DEXA scan.
What is a healthy body fat percentage?
For general health most adults do well in the “fitness” to “average” bands above. Very low body fat is not a health goal: below essential levels hormones, bone and immunity suffer. Rather than chasing a single number, watch the trend every 4–6 weeks under the same conditions.
Sources
- Hodgdon JA, Beckett MB. Prediction of percent body fat for U.S. Navy men and women from body circumferences and height. Naval Health Research Center, 1984
- American Council on Exercise (ACE), body fat percentage categories — https://www.acefitness.org/resources/everyone/tools-calculators/percent-body-fat-calculator/
- WHO, Obesity and overweight — https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight
This calculator is educational and not medical advice. If you have a health condition, are pregnant, or are under 18, ask a clinician before changing your diet.
What the result tells you
An estimate of your body-fat percentage from your BMI, age, and sex. It's a population estimate, not a direct measurement.
How to use it
- Use it to watch a trend over months, not to judge a single reading.
- Pair it with how your clothes fit and your waist measurement.
- For a real number, get calipers, a tape-measure method, or a DEXA scan.
Recommendations
- Changes of a few points take weeks — don't chase daily movement.
- Building muscle while losing fat can hide scale changes; body-fat trend tells more.
- Extremely low body fat isn't a health goal for most people.
Health & wellbeing
Body-fat targets are individual. Avoid fixating on a single 'ideal' number, especially if it drives restrictive eating.
Troubleshooting
Estimate seems off? It relies on BMI, so very muscular or very lean bodies read less accurately. A measured method will be closer.
How it’s calculated
This uses the Deurenberg equation, which estimates body fat from BMI, age, and sex — no calipers needed.
Body fat % = 1.20 × BMI + 0.23 × age − 10.8 × sex − 5.4 (men sex = 1, women sex = 0).
Source: Deurenberg P, et al., British Journal of Nutrition, 1991.
Common questions
Is the Navy method accurate?
Within a few percentage points for most people; least accurate for very lean or very muscular bodies.
Can I measure body fat with a scale?
Bio-impedance scales are convenient but swing with hydration; use them for trends, not absolute numbers.
What is a good body fat for a woman?
21–31% covers "fitness" to "average" for adults; athletes are lower.