Measure in a consistent way
Use a flexible measuring tape and keep it level around the body. Take measurements at the same points each time, ideally at a similar time of day and before a large meal or workout.
Body Fat Calculator
Estimate body fat percentage using body measurements or a BMI-based estimate.
years
Required for the BMI estimate.
cm
Measure without shoes.
kg
Use your current body weight.
Estimated body fat
| Estimated body fat percentage | — |
| General category | — |
| Estimated fat mass | — |
| Estimated lean mass | — |
Method used—
Body mass index—
Sex used—
Input weight—
This is a screening estimate, not a medical diagnosis. For clinical assessment or concerns about nutrition, weight, hormones, or health, consult a qualified health professional.
How it works
Make sense of body-fat estimates
This Body Fat Calculator uses either the US Navy circumference method or a BMI-based equation to estimate body fat percentage. These methods are convenient for tracking general changes over time, but they cannot replace a clinical assessment.
For the most meaningful comparisons, measure under similar conditions each time. Small differences in tape placement, hydration, posture, meals, exercise, or time of day can change circumference readings and therefore the estimate.
Choose the right method
The US Navy method uses height and circumferences. The BMI method uses height, weight, age, and sex. Both are estimates, so focus on practical trends rather than treating a single number as exact.
Track changes over time
Repeated measurements can show whether your overall body composition estimate is moving up or down. Pair the number with how you feel, energy levels, strength, fitness, and guidance from a qualified professional.
Know the limits
Body-fat estimates may be less accurate for some body types, athletes, older adults, and people with unusual fat distribution. Use the output as a helpful data point, not as a diagnosis or a reason to make extreme changes.
Frequently asked questions
The US Navy method estimates body fat from height and circumference measurements. For men, the equation uses waist and neck measurements. For women, it uses waist, hip, and neck measurements. The result is based on population formulas and should be treated as an approximation.
No home calculator can provide a clinical diagnosis. These equations can be useful for screening and trend tracking, but their accuracy varies among individuals. Professional methods such as DEXA scans, underwater weighing, or trained skinfold measurements may provide different estimates and also have limits.
The formula is different for men and women because average body-fat distribution patterns differ. The women's equation includes hip circumference alongside waist and neck measurements, which helps it estimate body composition from the measurements used by that method.
There is no single number that is healthy for every person. Body composition can vary with age, sex, genetics, training, medical history, and life stage. General categories are rough reference ranges only. If you have health-related questions, talk with a licensed medical or nutrition professional.
Body measurements can change slightly due to hydration, bloating, food intake, menstrual cycle, exercise, clothing, tape tension, posture, and where the tape is placed. For more consistent tracking, measure at a similar time and repeat the measurement two or three times before recording it.
It can help you observe broad trends, but it should not be the only tool used to guide health decisions. Sustainable health goals also involve nutrition, strength, sleep, mobility, mental well-being, and any medical conditions. Avoid using an estimate to justify restrictive or unsafe behaviors.