Body Fat Estimate Calculator using Waist to Height Ratio (RFM)

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On this page is a Body Fat Estimate Calculator. It uses waist to height ratio to estimate body fat percentage either measured by caliper or DXA scan.

Measure your height and waist in either meters and centimeters or feet and inches, enter your sex, and hit calculate for an estimate. Complete measurement instructions are given below the tool.

Body Fat Estimate Calculator

Note that for low body fat percentages – DXA estimates under 14% or so male and 24% female – the RFM estimate might be high. Use a caliper such as this one for more accuracy.

Measure Your Height and Waist Circumference

The RFM formula (basis for this tool and short for Relative Fat Mass) is based on 1999-2006 NHANES measurement microdata. You can read the 2015-16 guides for each measurement section here – check Anthropometry for the details.

Take a Waist Measurement

For the waist measurement, you'll need a flexible measuring tape such as this one from Amazon.

Your tape should stretch around the body at the level of the top of the left and right ileum on the hip. The ilium is the largest and highest bone in the hip:

NHANES manual waist measurement guidelines
Waist measurement location from the 2015-16 NHANES Field Manual

Take the measurement at the peak of an exhale, which will be the smallest measurement. Do not suck in.

Take a Height Measurement

Height should be measured with the buttocks, upper back, and back of head touching a flat vertical surface. Gaze should be forward, with the ear hole aligned with the bottom of the pupil (you most likely do this by default, but make sure your/the gaze is straight ahead).

Standing height measurement guidelines for NHANES 2015-2016
Height measurement from the 2015-16 NHANES Field Manual

Measure to the exact highest point on the head.

Body Fat Percentage Estimate Formula

Adult men and women have different base levels of muscle, essential fat, and fat distribution and it is reflected in the formula. The formula thus differs slightly for males and females:

Body Fat Estimate for Men

BF% = 64 − ( 20 * (height/waist) )

Body Fat Estimate for Women

BF% = 76 − ( 20 * (height/waist) )

Be sure you are using the same units for height and waist circumference

Healthy Body Fat Percentage

Disclaimer: nothing on DQYDJ is health advice. If you are concerned about your health because of body fat or otherwise, please consult a medical professional.

Since caliper and DXA estimates of body fat differ, we need to use two scales to present health breakpoints with body fat percentages. Our body fat percentage health status scale comes from ACE, the American Council on Exercise.

Anything in 'Acceptable' weight roughly maps to 'Overweight' in the BMI Calculator presented scale. 'Essential Fat' is 'Underweight' and can be quite hazardous. Men and women will likely encounter massive drive to eat food, and women of childbearing age might lose their menstrual cycle.

Please consult a medical professional for any advice, especially if these estimates put you on the extremes of the scale.

ACE Health Guidelines for Body Fat Percentage Ranges (Caliper)

Health RangeWomenMen
Essential Fat10-13%2-5%

ACE Health Guidelines for Body Fat Percentage Ranges (DXA Scan)

These are estimated for DXA based off the above caliper table.

Health RangeWomenMen
Essential Fat16.1-18.8%6.8-9.4%

Body Fat Percentage and DXA to Caliper to Conversion Methodology

The Waist-to-Height ratio to body fat percentage formula comes from Relative fat mass (RFM) as a new estimator of whole-body fat percentage ─ A cross-sectional study in American adult individuals Orison O. Woolcott & Richard N. Bergman (2018) (Link)

The caliper and DXA conversion methodology can be found inside our body fat comparison calculator.

Body Fat Percentage Distribution for Men and Women

Again, note that body fat percentage distribution and the distribution of fat itself differs for adult men and women. Starting around puberty, men and women will start to show different fat distribution patterns.

You can see the distribution of body fat percentages for men and women in the United States on this page:



PK started DQYDJ in 2009 to research and discuss finance and investing and help answer financial questions. He's expanded DQYDJ to build visualizations, calculators, and interactive tools.

PK lives in New Hampshire with his wife, kids, and dog.

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