Body Fat Calculator
Estimate body fat percentage using age, sex, height, weight and waist measurements. The result is a general estimate and not a direct measurement of body composition.
Calculate Estimated Body Fat
Choose metric or imperial units and enter the information requested below. This calculator uses the U.S. Navy circumference method as a general estimation method.
What Is Body Fat Percentage?
Body fat percentage describes the estimated proportion of a person's total body weight that consists of fat. It is different from body weight or BMI because it attempts to consider body composition.
An online calculator cannot directly measure body fat. It uses a mathematical equation and measurements to produce an estimate.
How This Calculator Estimates Body Fat
This calculator uses a circumference-based estimation method commonly referred to as the U.S. Navy method. It uses measurements such as height and waist circumference together with sex.
The method is designed to estimate body composition from easily obtained measurements rather than directly measuring body fat.
Why Weight Is Included
Weight is useful for estimating the amount of body mass represented by the calculated body-fat percentage. After estimating the percentage, the calculator can estimate fat mass and lean mass.
Estimated Lean Mass = Body Weight − Estimated Fat Mass
Example
Suppose a person weighs 70 kg and the calculator estimates body fat at 20%.
These values are estimates based on the calculated percentage and should not be treated as direct measurements.
Why Measurements Matter
Circumference-based formulas are sensitive to the measurements entered. Measuring at a different location, holding the tape differently or entering an incorrect value can change the result.
General Measurement Tips
- Use a flexible measuring tape.
- Keep the tape level where required by the method.
- Avoid pulling the tape excessively tight.
- Measure consistently when comparing results over time.
- Enter the measurement in the correct unit.
Body Fat Percentage vs BMI
BMI uses height and weight to produce a screening value. Body-fat percentage attempts to estimate the proportion of body weight represented by fat.
Both have limitations. Neither number provides a complete picture of individual health when considered alone.
Why Body Fat Estimates Can Differ
Different methods can produce different estimates. Bioelectrical impedance devices, skinfold measurements, circumference formulas and other methods are based on different assumptions.
Because of this, results from two different methods may not match exactly.
Common Body Fat Calculator Mistakes
- Entering the wrong unit.
- Measuring at the wrong location.
- Pulling the measuring tape too tightly or too loosely.
- Comparing results from different methods as if they were identical.
- Treating an estimate as an exact measurement.
Should Body Fat Percentage Be Used Alone?
No. Body composition is only one part of overall health. Physical activity, nutrition, medical history, fitness and many other factors can also matter.
For important health decisions, individualized guidance from a qualified healthcare professional may be more appropriate.
Who Should Use Extra Caution?
General body-composition calculators may not be suitable for every person or situation. Children, adolescents, pregnancy and certain medical conditions may require specialized assessment.
How to Use This Calculator
- Select Metric or Imperial.
- Select sex.
- Enter age.
- Enter height.
- Enter weight.
- Enter waist circumference.
- Select Calculate Body Fat.
- Review the estimated result.
Body Fat Calculator FAQ
Common questions about body fat estimates.
It provides an estimate of body fat percentage using a mathematical formula and the measurements entered by the user.
No. It estimates body fat using a circumference-based calculation method.
Weight is used with the estimated percentage to calculate estimated fat mass and lean mass.
No. The result is an estimate and can be affected by measurement technique and the method used.
Different methods can use different assumptions, so their results may not be directly comparable.
No. The calculator provides general educational information and should not replace individualized professional advice.