Body Fat Estimate
Estimate body fat percentage from circumference measurements and height.
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Free Body Composition Calculator
Body Fat Calculator Estimate Your Body Fat Percentage
Estimate body fat percentage, fat mass and lean body mass using simple body circumference measurements.
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Metric units
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US units
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Fat mass estimate
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Lean mass estimate
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Free Tool
Calculate Body Fat
Enter your measurements below
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cm
cm
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Measurement Tip
Use a flexible measuring tape and keep it level around the body without pulling it excessively tight. Consistent measurement technique improves repeatability.
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Body Fat Estimate Notice
Circumference-based body fat equations provide estimates. Results can vary with measurement technique, body shape and individual characteristics.
Calculator Features
Estimate Your Body Composition
Use simple body measurements to estimate body fat percentage, fat mass and lean mass.
Fat Mass Estimate
Estimate how much of the entered body weight corresponds to calculated fat mass.
Lean Mass Estimate
View estimated body weight remaining after calculated fat mass is subtracted.
Measurement Guide
How to Take Body Measurements
Consistent measurement technique is important because small differences in circumference values can change the estimated result.
Height
Stand upright and enter your height without shoes.
Neck
Measure around the neck with the tape positioned consistently and without excessive compression.
Waist
Measure the required waist or abdominal circumference consistently with the tape kept level.
Hip
For the female equation, measure around the widest portion of the hips.
Simple Process
How to Use the Body Fat Calculator
Choose Units
Select metric or US customary units.
Select Formula
Choose the sex-specific equation used for estimation.
Enter Measurements
Add height, weight and required circumference measurements.
View Estimate
See estimated body fat percentage, fat mass and lean mass.
Body Composition Guide
Free Online Body Fat Calculator
Our free online body fat calculator estimates body fat percentage using height and body circumference measurements. The calculator also uses body weight to estimate fat mass and lean mass.
You can use metric measurements in kilograms and centimeters or switch to US customary units using pounds, feet and inches.
What Is Body Fat Percentage?
Body fat percentage describes the estimated proportion of total body weight represented by fat mass. It is a body composition measure rather than a simple measurement of total weight.
For example, two people can have the same body weight but different estimated body fat percentages because their body composition may differ.
How Does the Body Fat Calculator Work?
This calculator uses a circumference-based estimation approach. For men, the equation uses height, neck circumference and waist or abdominal circumference. For women, the equation additionally uses hip circumference.
The result is a predictive estimate. It is not equivalent to directly measuring body composition with specialized clinical or laboratory equipment.
Body Fat Percentage vs BMI
Body fat percentage and Body Mass Index measure different things. BMI is calculated from weight relative to height, while a body fat estimate attempts to describe the proportion of body weight represented by fat.
Because the methods answer different questions, BMI and estimated body fat percentage should not be treated as interchangeable values.
Want to calculate BMI?
Use our free BMI calculator to calculate Body Mass Index from height and weight.
Open BMI Calculator Tools âWhat Is Fat Mass?
Fat mass is the estimated amount of total body weight represented by fat. In this calculator, estimated fat mass is calculated by multiplying body weight by the estimated body fat percentage.
Because fat mass depends on the estimated body fat percentage, it should also be interpreted as an estimate rather than a direct measurement.
What Is Lean Body Mass?
In this calculator, estimated lean mass is the body weight remaining after estimated fat mass is subtracted from total body weight.
Lean mass is not the same as muscle mass alone. The non-fat portion of body weight includes multiple tissues and body components.
Why Measurement Technique Matters
Circumference-based equations depend directly on the measurements entered. A tape placed at a different location, pulled too tightly or held at an angle can change the input value and therefore change the estimated result.
For progress tracking, use the same measurement technique and similar conditions each time. Consistency can make repeated estimates more useful for observing trends.
Can Body Fat Percentage Change Without Weight Change?
Body weight and body composition are different concepts. A person's total weight can remain relatively stable while the proportions of fat mass and non-fat mass change.
This is one reason body weight alone does not provide a complete description of body composition.
Is Lower Body Fat Always Better?
No. Body fat has physiological roles, and an extremely low percentage should not automatically be considered desirable. Appropriate interpretation depends on factors such as age, sex, individual circumstances and the method used to estimate body composition.
A calculator result should not be used by itself to set an extreme weight-loss or body-fat target.
How Accurate Is a Body Fat Calculator?
Online body fat calculators are predictive tools. Their estimates can differ from direct or instrument-based body composition assessments. Individual body shape and measurement technique can also affect results.
For that reason, this calculator is most appropriately treated as a general educational estimation tool.
Metric and US Unit Support
Metric mode accepts weight in kilograms and body measurements in centimeters. US mode accepts weight in pounds, height in feet and inches, and circumference measurements in inches.
The calculator handles the required unit conversion internally before applying the estimation equation.
Limitations of Circumference-Based Estimates
Circumference equations cannot capture every difference in body shape, fat distribution or body composition. Results can vary between individuals even when measurements appear similar.
Measurement error is another limitation. Small changes in neck, waist or hip measurements can alter the calculated estimate.
Important Information
This body fat calculator provides general estimates for educational purposes. It does not provide medical advice, diagnosis or individualized treatment. If body composition assessment is important for a medical or nutrition decision, seek appropriate professional guidance.
FAQ
Frequently Asked Questions
Body fat percentage is the estimated
proportion of total body weight represented
by fat mass.
It uses a circumference-based predictive
equation with height and selected body
measurements. Men use neck and waist
measurements, while women additionally
use hip circumference.
No. Online body fat calculators provide
estimates and do not directly measure
body composition.
The calculator requires height, weight,
neck circumference and waist circumference.
The female equation also requires hip
circumference.
Yes. Select metric units for centimeters
and kilograms or US units for inches,
feet and pounds.
No. In this calculator, estimated lean
mass means body weight remaining after
estimated fat mass is subtracted. It is
not a direct measurement of muscle mass.