How to use the body fat athlete calculator
Prepare the values for this calculation
Estimate adult body-fat percentage from the Jackson–Pollock seven-site skinfold method. The equation is a generalized adult regression commonly used in fitness settings; it is not athlete-specific and may be biased in some athletic populations. Use the formula below to check that it answers your question. Read the input units before transferring figures from a statement, measurement or dataset.
Enter and check each input
- Sex used by the published equation: choose Male equation, Female equation. Match this selection to the data you enter.
- Age (years): enter a value at least 18 and no more than 61 and a whole number. Use the unit named in the label or selected above. Do not leave this required field blank.
- Chest skinfold (mm): enter a value at least 0.1 and no more than 100. Use the unit named in the label or selected above. Do not leave this required field blank.
- Midaxillary skinfold (mm): enter a value at least 0.1 and no more than 100. Use the unit named in the label or selected above. Do not leave this required field blank.
- Triceps skinfold (mm): enter a value at least 0.1 and no more than 100. Use the unit named in the label or selected above. Do not leave this required field blank.
- Subscapular skinfold (mm): enter a value at least 0.1 and no more than 100. Use the unit named in the label or selected above. Do not leave this required field blank.
- Abdomen skinfold (mm): enter a value at least 0.1 and no more than 100. Use the unit named in the label or selected above. Do not leave this required field blank.
- Suprailiac skinfold (mm): enter a value at least 0.1 and no more than 100. Use the unit named in the label or selected above. Do not leave this required field blank.
- Thigh skinfold (mm): enter a value at least 0.1 and no more than 100. Use the unit named in the label or selected above. Do not leave this required field blank.
The input table gives a complete example. Keep units and time periods consistent across related fields.
Calculate and resolve any input error
Choose Calculate after entering the values. Changes also update the answer after a short pause. If an error appears, follow its message, correct the field and calculate again. Reset restores the example values.
Interpret the answer
Check Estimated body fat first. With the unchanged example inputs, it is 10.21%. Compare the additional metrics with the primary result; each has its own label and unit.
Compare and keep a useful result
For a controlled comparison, keep every other example input unchanged and change Age (years) from 30 to 33. The resulting Estimated body fat is 10.58%. This illustrates the equation’s response to that input, rather than a forecast of real events.
Read the chart’s axis labels and data table. A scenario curve changes one stated input while holding the others fixed; it does not add external observations. Use Download graph to save an available chart as a PNG.
Use Copy result or Download CSV to keep the answer. Share tool shares the page address without placing your input values in the URL. Recheck inputs and assumptions before using the result for a decision.
Body Fat Athlete Calculator formula
Men: BD = 1.112 − 0.00043499S + 0.00000055S² − 0.00028826A. Women: BD = 1.097 − 0.00046971S + 0.00000056S² − 0.00012828A. S is the sum of seven skinfolds in millimetres. Siri conversion: body fat % = 495/BD − 450.
Inputs and units
| Input | Format / range | Example |
|---|---|---|
| Sex used by the published equation | Select an option | Male equation |
| Age (years) | minimum 18; maximum 61; whole number | 30 |
| Chest skinfold (mm) | minimum 0.1; maximum 100 | 8 |
| Midaxillary skinfold (mm) | minimum 0.1; maximum 100 | 8 |
| Triceps skinfold (mm) | minimum 0.1; maximum 100 | 10 |
| Subscapular skinfold (mm) | minimum 0.1; maximum 100 | 10 |
| Abdomen skinfold (mm) | minimum 0.1; maximum 100 | 14 |
| Suprailiac skinfold (mm) | minimum 0.1; maximum 100 | 9 |
| Thigh skinfold (mm) | minimum 0.1; maximum 100 | 11 |
Worked example
Using the example inputs above, the estimated body fat is 10.21%.
- Estimated body fat
- 10.21%
- Body density
- 1.075598 g/cm³
- Sum of 7 skinfolds
- 70 mm
- Protocol
- Chest + midaxillary + triceps + subscapular + abdomen + suprailiac + thigh
Results and assumptions
This is the generalized adult Jackson–Pollock 7-site skinfold estimate with the Siri density conversion. It is often used in sport and fitness settings, but it is not an athlete-specific equation and may be biased in some homogeneous athletic populations. Caliper, landmarking and technician technique materially affect the estimate; it is not a diagnosis or direct body-fat measurement.
Sources and method references
Fix an input or unexpected result
Age (years) is required. Enter age (years) using the format and bounds in the input table. Zero and an empty field are different: use zero only if it is allowed and represents your data.
If your answer differs from the example, choose Reset and compare every field, including selected units and options. Check percentage versus decimal entry and whether values describe the same period. Round only the final displayed answer when reproducing the formula.
If a discrepancy remains, report the calculator issue with the page address, non-sensitive example inputs, actual result, expected result and a reference for your calculation.