Fitness & Health

Body Fat Calculator

Estimate body fat percentage from key measurements.

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Inputs

Compare US Navy tape method and BMI-based estimates.

SexAgeTarget body fat (%)Weight (kg)Height (cm)Waist (cm)Neck (cm)

Results

Estimated body fat percentage.

US Navy method

18.46%

BMI method

20.33%

Fat mass

14.77 kg

Lean mass

65.23 kg

Target weight

79.55 kg

Fat to change

0.45 kg

Waist-to-hip ratio

0.95

Waist-to-height ratio

0.5

Body composition snapshot

Metric	Value
Current weight	80 kg
Body fat (selected)	18.46%
Fat mass	14.77 kg
Lean mass	65.23 kg
Target body fat	18%
Target weight	79.55 kg
Target fat mass	14.32 kg
Fat to change	0.45 kg
Waist-to-hip ratio	0.95
Waist-to-height ratio	0.5

Category ranges

Range	Percent
Essential	2-5%
Athletes	6-13%
Fitness	14-17%
Average	18-24%
High	25%+

Ranges are generalized and vary by age and source.

How this calculator works

Estimates body fat percentage using both the US Navy circumference method and a BMI-based method. It uses tape measurements or BMI plus age/sex to provide quick screening estimates rather than clinical measurements.

Quick guide

Jump straight to the section you need, then return to the calculator.

Inputs Outputs Assumptions Tips Formulas Examples Reference table Visual breakdown References

Inputs

Sex selection
Age in years for BMI-based estimates
Target body fat percentage
Body weight in kg or lb
Height, waist, and neck circumference in cm or inches
Hip circumference in cm or inches for females
Consistent tape measurement technique

Outputs

Estimated body fat percentage (US Navy)
Estimated body fat percentage (BMI method)
Fat mass and lean mass estimates
Target weight based on current lean mass
Fat to lose or gain to reach the target
Result clamped to a 0-100 percent range

Assumptions

Tape measurements are accurate and taken at standard sites
Units are converted internally between cm and inches
Method is an estimate and not a clinical test

Tips

Measure at the same time of day for consistency
Keep the tape level and snug but not tight
Track trends instead of single measurements

Formula guide

Use these formulas to audit the output or explain it to someone else.

6 formulas

Male: 86.010*log10(waist-neck) - 70.041*log10(height) + 36.76

Female: 163.205*log10(waist+hip-neck) - 97.684*log10(height) - 78.387

BMI method (adult male): 1.20*BMI + 0.23*age - 16.2

BMI method (adult female): 1.20*BMI + 0.23*age - 5.4

BMI method (boys): 1.51*BMI - 0.70*age - 2.2

BMI method (girls): 1.51*BMI - 0.70*age + 1.4

Usage examples

Review a ready-made scenario, copy it, then tweak inputs to match your case.

Example

2 inputs2 outputs

Male example

Inputs

Male, height 180 cm
Waist 90 cm and neck 40 cm

Outputs

Body fat about 18%
Result is a screening estimate

Small changes in tape placement can move the result.

Example

2 inputs2 outputs

Female example

Inputs

Female, height 165 cm
Waist 75 cm, neck 35 cm, hip 95 cm

Outputs

Body fat about 26%
Result is a screening estimate

Use consistent technique to track changes over time.

General body fat ranges (male)

5 of 5 rows

Range	Percent	Note
Essential	2-5	Minimum healthy range
Athletes	6-13	Competitive fitness
Fitness	14-17	Lean and fit
Average	18-24	Typical range
High	25+	Elevated body fat

Ranges vary by source and are not medical thresholds.

Body fat scenarios

Highest: High (28%)Lowest: Lean (12%)

Sort

ScenarioBody fat percent

Focus point

Lean

12%

Position

#1 of 4

Original order

Share of total

15.19%

Total: 79%

PositiveNegative

Use ranges for context rather than exact targets.

Estimate only and not a medical diagnosis.

References

US Navy body fat method
Circumference-based body composition formulas

FAQ

Common questions

What does the Body Fat Calculator do?

What inputs do I need?

Typical inputs include Sex selection, Age in years for BMI-based estimates, Target body fat percentage.

How are the results calculated?

We follow the formulas and assumptions outlined in the "How this calculator works" section. You will see outputs like Estimated body fat percentage (US Navy), Estimated body fat percentage (BMI method), Fat mass and lean mass estimates.