Body Fat Percentage Calculator
Enter Body Measurements
Estimate body fat percentage, fat mass, lean mass, and target weight from body measurements or a BMI-based formula.
Quick presets
Primary calculation method
Basic Body Details
Body Circumferences
Body Fat Results
Body circumference method
Average rangeEstimated body fat
18.6%
Fat mass
14.9 kg
Lean mass
65.1 kg
BMI
26.12
Waist-to-height ratio
0.50
Target weight
76.6 kg
Estimated by assuming lean mass stays the same.
Weight to lose
3.4 kg
Method Comparison
The circumference and BMI methods use different inputs and assumptions, so their estimates can differ.
Body circumference method
18.6%
BMI-based quick estimate
22.0%
Measurement Guide
Neck
Measure around the neck comfortably.
Waist
Measure while standing naturally without pulling in your stomach.
Hip
Used for the female formula. Measure around the widest part of the hips.
Do not pull the tape too tight or leave it too loose.
This calculator estimates body fat percentage using body circumference or BMI-based formulas. Status labels are general reference ranges and can be interpreted differently by age and individual health. Actual body fat can vary depending on measurement method, hydration, tape position, muscle mass, and body shape. It does not replace medical evaluation or professional body composition testing.
Usage Tips
Measure at the same time and tape position to compare trends
Take neck, waist, and hip measurements under similar conditions, such as in the morning with the same posture and tape placement. Use repeated measurements to compare trends rather than treating one estimate as a professional body-composition test.
What is Body Fat Percentage Calculator?
The Body Fat Percentage Calculator estimates body fat percentage, fat mass, and lean mass from sex, age, height, weight, and body circumferences. It compares the standard U.S. Navy circumference formula with a quick BMI-based estimate and calculates a theoretical target weight under the assumption that lean mass remains unchanged.
How to Use
- 1Enter sex, age, height, and weight, then choose the preferred units.
- 2Measure and enter neck and waist circumference, plus hip circumference for the female formula.
- 3Choose the circumference or BMI-based method as the primary result.
- 4Enter a target body fat percentage to estimate target weight while holding lean mass constant.
- 5Review both method estimates, the status label, and waist-to-height ratio together.
Reference Knowledge
- ●The standard U.S. Navy method converts body circumferences to inches and applies a sex-specific logarithmic equation.
- ●The BMI-based estimate uses only BMI, age, and sex adjustment, so it is quick but cannot fully account for individual muscularity or body shape.
- ●Fat mass equals body weight multiplied by body fat percentage, while lean mass equals body weight minus fat mass.
- ●Target weight equals lean mass divided by one minus the target body fat fraction and assumes lean mass does not change.
- ●Waist-to-height ratio divides waist circumference by height and is a supplementary indicator rather than a direct body-fat measurement.
- ●Tape position, breathing, hydration, meals, and recent exercise can change measurements, so repeated checks should use similar conditions.
FAQ
Q.How does the U.S. Navy body fat formula work?
The male equation uses height, waist, and neck measurements, while the female equation also uses hip circumference. Measurements are converted to inches and entered into sex-specific logarithmic equations to provide a practical estimate without specialized equipment.
Q.Why do the Navy and BMI estimates differ?
The Navy method uses circumferences related to body-fat distribution, while the BMI method uses only height, weight, age, and sex. Differences can be larger for people whose muscularity or body shape differs from the population averages behind either formula.
Q.Should I use the target weight as a strict weight-loss goal?
No. The result assumes current lean mass remains unchanged. Water, muscle mass, training status, and measurement error can change during weight loss, so use the number as a comparison reference rather than a diet prescription.
Q.When should I take body circumference measurements?
Measure under similar conditions, such as in the morning with a relaxed posture and consistent hydration. Keep the tape level and lightly touching the skin without compressing it, and use the same anatomical location each time.
Q.Why can this result differ from BIA or DEXA testing?
Circumference formulas estimate from body shape, BIA devices infer composition from electrical resistance, and DEXA uses imaging. Each method has different assumptions and errors, so results may not match. Professional evaluation should take priority for medical decisions.
