Body Fat Calculator
Estimate body fat from height, weight, age, and sex, and see its category.
Once all are filled in, the result switches to the tape formula, which has a smaller margin of error.
Estimated from BMI, age, and sex. The range reflects the formula’s standard error of estimate, ±4.1 percentage points.
Body fat here is an estimate from a formula, and these categories are not medical diagnostic criteria. Talk to a professional about your health.
Body fat categories
About 18% body fat falls in the Acceptable category.
From the American Council on Exercise (ACE). The black line under the bar is the margin of error, and fat mass uses the weight you entered.
| Category | Body fat | Fat mass |
|---|---|---|
| Essential fat | 2–5% | 3.1–7.7 lb |
| Athletes | 6–13% | 9.2–20 lb |
| Fitness | 14–17% | 21.6–26.2 lb |
| Acceptable | 18–24% | 27.7–37 lb |
| Obesity | 25%+ | 38.5+ lb |
Body Fat Calculator
Body Fat Calculator estimates how much of your weight is fat using published formulas. It works from your height, weight, age, and sex, and uses the tape formula if you have measurements.
Fat mass = weight × body fat %
150 lb × 20% = 30 lb
Results are approximate values, not a diagnosis. Decimals would look more exact than these methods are, so body fat is rounded and shown with a range of one standard error. Your true value can still fall outside it.
How to use
- Enter your height, weight, sex, and age.
- Read your estimated body fat, its range, fat mass, and lean mass on the right.
- Use the table below to see where you sit and how much fat each category means. Categories change with sex.
- If you have tape measurements, check the box and enter your neck and waist, plus hips if you are female. The result then comes from your body measurements instead of BMI, which can’t tell muscle from fat, and the standard error drops from 4.1 points to 3.52 for men and 3.72 for women.
Key terms
Body fat categories
These follow the table from the American Council on Exercise (ACE), which is split by sex. Values are rounded so that none falls between two ranges.
| Category | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Acceptable | 18–24% | 25–31% |
| Obesity | 25% or more | 32% or more |
Fat mass and lean mass
- Fat mass: your weight times your body fat percentage.
- Lean mass: what remains of your weight, including muscle, bone, and water.
Body fat equations
The equation depends on what you enter. The standard error shows how far an estimate tends to fall from the true value.
| Equation | Needs | Standard error |
|---|---|---|
| Deurenberg (1991) | Height, weight, age, sex | 4.1 points |
| U.S. Navy (1984) | Height, neck, waist, hips if female | Men 3.52, women 3.72 |
Deurenberg equation
BMI = weight (kg) ÷ height (m)²
Body fat = 1.20 × BMI + 0.23 × age − 10.8 × sex (male 1, female 0) − 5.4
A 30-year-old man with a BMI of 22.7 comes out at about 18%. The paper notes that it slightly overestimates body fat in people with obesity.
U.S. Navy equations
Measurements are in cm. The coefficients come from a 1998 Institute of Medicine report.
Men: density = −0.191 × log₁₀(waist − neck) + 0.155 × log₁₀(height) + 1.032
Women: density = −0.350 × log₁₀(waist + hips − neck) + 0.221 × log₁₀(height) + 1.296
Body fat = 100 × (4.95 ÷ density − 4.5)
A man who is 69 in tall with a 15 in neck and 33 in waist comes out at about 16%.
How fast can body fat come down?
ACE explains that no official guidelines exist for body fat loss, and describes about 1% per month as generally safe and doable.
Measuring methods have error, so a small change may not be a real one. ACE suggests waiting a couple of months before checking again.
How to measure
- Men’s waist: level with the navel.
- Women’s waist: the narrowest point between the bottom of the breastbone and the navel.
- Neck: just below the voice box.
- Hips: the widest point.
Keep the tape level without pressing into the skin, and to track change, measure the same way at the same time of day.
FAQ
Can I estimate body fat without a tape measure?
Yes. It is estimated from your weight, height, age, and sex. If you do measure, you can use the tape formula too.
Why does this differ from my body composition scale?
This calculator estimates with formulas, and scales measure a different way, so results can differ. Either way, repeating the same method is the best way to see change.
Why are the categories different for men and women?
The ACE table this calculator follows sets separate ranges by sex, so the categories change with the sex you choose.
Can teens use this?
No. The equations here are for adults, so it only calculates for ages 20 and up.
Is what I enter saved?
No. It is never saved or sent to a server. Everything is calculated in your browser.