How to use the body fat from navy formula calculator
Prepare the values for this calculation
Estimate body-fat percentage with the Hodgdon–Beckett U.S. Navy circumference equations. This is the direct regression formula, not an official current Navy BCA determination. 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
- Measurement units: choose Inches, Centimeters. Match this selection to the data you enter.
- Sex used by the published equation: choose Male equation, Female equation. Match this selection to the data you enter.
- Height: enter a value at least 1 and no more than 300. Use the unit named in the label or selected above. Do not leave this required field blank.
- Neck circumference: enter a value at least 0.1 and no more than 200. Use the unit named in the label or selected above. Do not leave this required field blank.
- Abdominal / waist circumference: enter a value at least 0.1 and no more than 300. Use the unit named in the label or selected above. Do not leave this required field blank.
- Hip circumference (female equation only): enter a value at least 0.1 and no more than 300. 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 17.51%. 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 Height from 70 to 77. The resulting Estimated body fat is 14.61%. 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 from Navy Formula Calculator formula
Male: %BF = 86.010 log10(abdomen − neck) − 70.041 log10(height) + 36.76. Female: %BF = 163.205 log10(waist + hip − neck) − 97.684 log10(height) − 78.387. The published direct equations use inches; metric inputs are converted to inches first.
Inputs and units
| Input | Format / range | Example |
|---|---|---|
| Measurement units | Select an option | Inches |
| Sex used by the published equation | Select an option | Male equation |
| Height | minimum 1; maximum 300 | 70 |
| Neck circumference | minimum 0.1; maximum 200 | 15 |
| Abdominal / waist circumference | minimum 0.1; maximum 300 | 34 |
| Hip circumference (female equation only) | minimum 0.1; maximum 300 | 39 |
Worked example
Using the example inputs above, the estimated body fat is 17.51%.
- Estimated body fat
- 17.51%
- Circumference value used
- 19 in
- Height used by equation
- 70 in
- Equation
- Hodgdon–Beckett male
Results and assumptions
This is an estimate from the published circumference regression, not a direct body-fat measurement or an official current Navy BCA result. Current Navy procedures prescribe measurement technique, rounding and table lookup; use current Navy guidance for an official assessment.
Sources and method references
- Hodgdon & Beckett (1984) — Prediction of Percent Body Fat for U.S. Navy Men from Body Circumferences and Height
- Hodgdon & Beckett (1984) — Prediction of Percent Body Fat for U.S. Navy Women from Body Circumferences and Height
- U.S. Navy Physical Readiness Program Guide 4 — Body Composition Assessment (Jan. 2024)
Fix an input or unexpected result
Height is required. Enter height 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.