Body Fat Calculator
Estimate body fat using the U.S. Navy method and the BMI method. Enter measurements to the nearest 0.5 cm (or 1/4 inch).
The Body Fat Calculator estimates your total body fat using your measurements. Use the Metric Units tab if you prefer the International System of Units (SI). For best accuracy, measure to the nearest 0.5 cm (1/4 inch). This calculator implements the U.S. Navy method and also shows an estimate based on the BMI method—both formulas and measurement instructions are provided below.
How to use
Enter your details and click Calculate. You can switch between US units, metric units, and other units. Typical fields include:
Gender
Age (years)—e.g., 25
Weight—e.g., 70 kg
Height—e.g., 178 cm
Neck circumference—e.g., 50 cm
Waist circumference—e.g., 96 cm
Hip circumference (females only)
Example result (illustrative)
Body Fat (U.S. Navy method): 15.7%
Body Fat Category: Fitness
Body Fat Mass: 11.0 kg
Lean Body Mass: 59.0 kg
Ideal Body Fat for a Given Age (Jackson & Pollock): 10.5%
Body Fat to lose to reach ideal: 3.6 kg
Body Fat (BMI method): 16.1%
Related tools
BMI Calculator | Calorie Calculator | Ideal Weight Calculator
Reference tables
American Council on Exercise—Body Fat Categories
Description
Women
Men
Essential fat
10–13%
2–5%
Athletes
14–20%
6–13%
Fitness
21–24%
14–17%
Average
25–31%
18–24%
Obese
32%+
25%+
Jackson & Pollock—Typical ideal body fat by age
Age
Women
Men
20
17.7%
8.5%
25
18.4%
10.5%
30
19.3%
12.7%
35
21.5%
13.7%
40
22.2%
15.3%
45
22.9%
16.4%
50
25.2%
18.9%
55
26.3%
20.9%
Body fat, overweight and obesity—a short overview
Body fat (adipose tissue) stores energy and produces hormones; it also provides insulation and physical cushioning. Body fat is commonly described as
Essential fat: necessary for normal physiological function (approximately 2–5% in men, 10–13% in women).
Storage fat: includes subcutaneous fat (beneath the skin) and visceral fat (around internal organs). While some storage fat is healthy, excess storage fat raises the risk of many health problems.
Being overweight does not always mean excess body fat—weight comprises fat, muscle, bone, and water. Very muscular people may be classified as overweight despite low body fat.
Fat distribution and the rate of fat gain differ by individual, affected by genetics, diet, exercise, and age. After about age 40 (or following menopause for some women), changes in sex hormones often lead to more abdominal fat in men and more fat around the hips and thighs in women.
Health risks of excess body fat
Excess body fat—especially abdominal visceral fat—raises the risk of many health problems, including:
Cardiovascular disease and stroke
Type 2 diabetes and insulin resistance
Certain cancers
Obstructive sleep apnoea
Reduced quality of life and poorer mental-health outcomes
Visceral fat can disrupt hormonal balance and increase inflammatory proteins (cytokines), raise LDL (“bad”) cholesterol, and lower HDL (“good”) cholesterol. The World Health Organization and public health bodies classify obesity as a leading preventable cause of death and illness.
Measuring body fat percentage
U.S. Navy method
The U.S. Navy method uses body circumferences and height. Measurements should be taken as follows:
Waist (men): measure horizontally at the navel. Do not suck the stomach in.
Waist (women): measure at the narrowest point.
Neck: measure just below the larynx, with the tape sloping slightly down at the front. Avoid bulging the neck out.
Hips (women only): measure at the widest horizontal point.
Equations
Metric (SI) formulations used by the Navy method:
Men
BFP=4951.0324−0.19077×log10(waist−neck)+0.15456×log10(height)−450 \text{BFP} = \frac{495}{1.0324 – 0.19077 \times \log_{10}(\text{waist} – \text{neck}) + 0.15456 \times \log_{10}(\text{height})} – 450 BFP=1.0324−0.19077×log10(waist−neck)+0.15456×log10(height)495−450
Women
BFP=4951.29579−0.35004×log10(waist+hip−neck)+0.22100×log10(height)−450 \text{BFP} = \frac{495}{1.29579 – 0.35004 \times \log_{10}(\text{waist} + \text{hip} – \text{neck}) + 0.22100 \times \log_{10}(\text{height})} – 450 BFP=1.29579−0.35004×log10(waist+hip−neck)+0.22100×log10(height)495−450
(US customary versions use inches and different coefficients; many calculators provide both.)
Notes: Results are estimates. For higher accuracy, consider bioelectrical impedance analysis, DEXA scans, or hydrostatic weighing.
Fat mass and lean mass
Fat mass (FM) = Body fat fraction × Weight
Lean mass (LM) = Weight − Fat mass
These help quantify how much of your weight is fat versus lean tissue.
BMI method (alternative estimate)
BMI-based formulas give an approximate body-fat percentage from BMI and age.
Adult men:
BFP=1.20×BMI+0.23×Age−16.2\text{BFP} = 1.20 \times \text{BMI} + 0.23 \times \text{Age} – 16.2 BFP=1.20×BMI+0.23×Age−16.2
Adult women:
BFP=1.20×BMI+0.23×Age−5.4\text{BFP} = 1.20 \times \text{BMI} + 0.23 \times \text{Age} – 5.4 BFP=1.20×BMI+0.23×Age−5.4
Boys:
BFP=1.51×BMI−0.70×Age−2.2\text{BFP} = 1.51 \times \text{BMI} – 0.70 \times \text{Age} – 2.2 BFP=1.51×BMI−0.70×Age−2.2
Girls:
BFP=1.51×BMI−0.70×Age+1.4\text{BFP} = 1.51 \times \text{BMI} – 0.70 \times \text{Age} + 1.4 BFP=1.51×BMI−0.70×Age+1.4
Limitations: BMI does not distinguish between fat and muscle. These formulas therefore only provide a rough estimate of body fat.