Body Mass For Men
Estimate body fat percentage and lean body mass with the Jackson–Pollock 7-site method for men. Enter your age, weight, and seven skinfold measurements.
7-Point Skinfold Calculator for Men
Body Mass For Men Formula
Where:
- \(S\) — sum of the seven skinfold measurements (mm).
- \(P, Ab, T, Tr, Sb, Si, Ax\) — pectoral, abdominal, thigh, triceps, subscapular, suprailiac, and axilla folds, respectively (mm).
- \(A\) — age (years); \(W\) — weight (kg).
- \(D\) — estimated body density; \(BF\) — body fat percentage; \(LBM\) — lean body mass (kg).
The Jackson–Pollock equation estimates body density from age and seven skinfolds. The calculator converts that density to body fat percentage, then uses weight to estimate lean body mass.
Body Mass For Men – Calculation Example
Example: A 30-year-old man weighs 75 kg. His pectoral, abdominal, thigh, triceps, subscapular, suprailiac, and axilla folds are 10, 20, 18, 12, 15, 14, and 11 mm.
\[S=10+20+18+12+15+14+11=100\text{ mm}\]
\[D=1.112-0.00043499(100)+0.00000055(100)^2-0.00028826(30)=1.0653532\]
\[BF=\frac{495}{1.0653532}-450\approx14.63\%\]
\[LBM=75\left(1-\frac{14.6346}{100}\right)\approx64.02\text{ kg}\]
Result: About 14.63% body fat and 64.02 kg lean body mass.
How to use the calculator
- Enter your Age in years and Weight in kilograms.
- Measure and enter the Pectoral fold, Abdominal fold, and Thigh fold in millimeters.
- Enter the Triceps fold, Subscapular fold, Suprailiac fold, and Axilla fold in millimeters.
- Read the estimated Body fat percentage and Lean body mass in kilograms.
Use skinfold calipers rather than a tape measure. Each entry is the thickness of a pinched fold of skin and underlying fat—not the circumference of that body part. The calculator requires all seven sites; leaving one out changes the sum and makes the estimate unreliable.
What the results mean
Body fat percentage estimates the proportion of your total weight that is fat. The Jackson–Pollock 7-site method uses folds from the chest, abdomen, thigh, back of the upper arm, below the shoulder blade, above the hip, and side of the torso. These measurements estimate body density; a second equation converts density into a body fat percentage.
Lean body mass is your estimated weight minus estimated fat mass. It includes muscle, but also water, bones, organs, and other non-fat tissue. For example, the 64.02 kg result above does not mean the person has 64.02 kg of muscle. Because lean body mass depends on the estimated body fat percentage, an error in the skinfold estimate also affects the lean mass result.
These results can be useful for following changes over time alongside weight and other measurements. A single percentage is not a diagnosis or a complete picture of health: the method does not show where internal fat is stored or distinguish changes in muscle from changes in body water. For a different measure based on height and weight, use the Body Mass Index calculator. For another body fat estimate that does not require calipers, see the Circumference Bodyfat calculator.
Measurement tips and limitations
Skinfold technique matters. Use the same established site locations and measurement procedure each time. Pinch the skin and underlying fat without including muscle, place the calipers beside your fingers, and take repeat readings at each site. If readings differ noticeably, repeat them rather than relying on one attempt. A trained measurer can help improve consistency, especially at sites that are difficult to reach yourself.
For comparisons over time, measure under similar conditions and, where possible, have the same person use the same calipers. Hydration, recent exercise, site placement, and differences between measurers can all affect readings. Look for a sustained trend rather than treating a small change in the displayed percentage as a precise change in body fat.
This calculator uses the men’s Jackson–Pollock equation; the Body Mass for Women calculator uses a different equation. Although the Age field accepts values from 10 years upward, an accepted input is not a guarantee that this equation is appropriate for children or adolescents. Estimates may also be less reliable when skinfolds do not reflect overall body fat well. If you need an assessment for a clinical or athletic decision, discuss the measurement method and result with a qualified professional.
Frequently Asked Questions
How can I calculate fat mass from the results by hand?
Multiply your weight by your body fat percentage expressed as a decimal. For example, at 75 kg and 20% body fat, estimated fat mass is 75 × 0.20 = 15 kg. You can also subtract lean body mass from total weight. Both calculations depend on the accuracy of the original skinfold estimate.
What is a healthy body fat percentage for men?
There is no single healthy percentage for every man. Age, health, and athletic goals all affect how a result should be interpreted. Broad reference ranges can provide context, but they are not diagnostic cutoffs, and a very low percentage is not necessarily better. If your result concerns you, discuss it alongside other health measures with a qualified professional.
Can I enter weight in pounds or skinfolds in centimeters?
Convert measurements before entering them: divide pounds by 2.20462 to get kilograms, and multiply centimeters by 10 to get millimeters. If a fold is recorded in inches, multiply it by 25.4 to get millimeters. Entering the correct number in the wrong unit can produce a misleading result, even if the calculator accepts it.
Why did I get a negative or unusually high body fat percentage?
An implausible result usually means an input or measurement needs checking. Look for unit errors, a misplaced decimal point, or folds measured at the wrong locations. The equation can also produce unrealistic outputs for measurements outside the range where it performs well; accepting an entry does not validate the estimate. Do not interpret an impossible percentage as a real body composition measurement.
Does changing my weight change the estimated body fat percentage?
No. In this method, age and the seven skinfolds determine the estimated body fat percentage; weight is used afterward to calculate lean body mass. If you change only your weight, the percentage stays the same while the estimated lean mass changes. After a substantial weight change, take new skinfold measurements rather than relying on the old percentage.
Can I use three skinfold readings instead of seven?
No. A three-site test uses a different equation and prescribed measurement sites; it is not a shortened version of this calculation. Substituting sites or treating missing folds as zero changes the input the seven-site equation expects. If you only have three readings, use a calculator designed for that specific protocol and compare trends using the same method each time.
How often should I repeat skinfold measurements?
Every few weeks is generally more useful than measuring daily. Small short-term differences can come from technique and measurement conditions rather than a real change in body fat. Record the readings as well as the calculated percentage, and compare measurements taken with the same procedure. Seek professional guidance if you need a more precise assessment for a health or athletic decision.