Body Fat Percentage Calculator
Circumference body composition
Enter consistent tape measurements
Result
Calculation summary
Enter values to see the result
Composition preview
Estimated fat and lean mass
How to use this calculator
- 1Measure height, neck, and waist consistently; the female equation also requires hip circumference.
- 2Enter body weight to split the percentage estimate into fat mass and lean mass.
- 3Repeat measurements at the same landmarks and conditions when tracking change.
Formula
Circumference estimate = a × log₁₀(combined girths) − b × log₁₀(height) + c
The male profile uses waist minus neck; the female profile uses waist plus hip minus neck. Measurements are normalized to inches.
Calculation steps
- Convert all circumferences and height to inches and weight to kilograms.
- Apply the selected circumference equation without mixing measurement profiles.
- Multiply estimated percentage by body weight to derive fat mass and subtract it to derive lean mass.
Worked example
Using the male profile with 175 cm height, 38 cm neck, 84 cm waist, and 70 kg weight produces an estimate of about 16.2% body fat.
Assumptions
- The tape is level, snug without compressing skin, and placed at consistent anatomical landmarks.
- The selected male or female profile determines which published equation and measurements are used.
- Hydration, breathing, posture, tape placement, and rounding can change the estimate.
- The result is not equivalent to DEXA, air displacement, underwater weighing, or clinical assessment.
Sources
Frequently asked questions
How tight should the tape be?
Keep it level and snug against the skin without compressing soft tissue. Use the same tape and landmarks for repeat measurements.
Why does a small measurement change affect the result?
The method subtracts or combines circumferences inside a logarithmic equation, so neck, waist, hip, placement, and rounding all matter.
Is this more accurate than BMI?
It estimates a different quantity, but both are indirect screening tools with individual error. Neither is a clinical body-composition measurement.
Why is sex required?
The published circumference method uses different measurement combinations and coefficients for its male and female formula profiles.