Enter your measurements
Keep one unit system throughout. The legacy circumference estimate uses height, neck and waist (plus hip for women). The Deurenberg estimate uses height, weight, age and sex.
Results
Enter your measurements and choose a method to estimate body fat percentage.
Please check the highlighted fields and try again.
Body fat percentage
Category
Fat mass
Lean mass
For information only; measurement methods and individual factors vary. Not a medical diagnosis.
Category ranges
These ranges are typical reference values for each category. Use your full context (training status, age, hydration, method) when interpreting results.
| Category | Range |
|---|
Category visualization
This visual bar shows where the estimated body fat percentage sits across category bands. It helps you spot trend changes and boundary effects.
Measure consistently
- Neck: place the tape just below the larynx, looking forward, level and snug without compressing the skin.
- Waist for men: measure horizontally at the navel after a gentle exhale.
- Waist for women: measure the narrowest natural waist after a gentle exhale.
- Hip for women: measure around the fullest part of the hips and buttocks.
- Repeatability: use the same time of day and conditions, take two or three readings, and compare the same formula over time.
Interpret the result as a trend
The equations estimate body fat indirectly; they do not measure it. Tape placement, hydration, muscle mass, body shape, age and rounding can all change the result.
Fat and lean mass are calculated from the unrounded percentage and rounded only for display. The category bands are general adult reference descriptions, not diagnoses, treatment targets or personalized medical advice.
If precision will affect medical, nutrition or training decisions, discuss an appropriate method with a qualified professional. A clinical method such as DEXA can still differ from other methods.
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When to use this calculator
Use it for a repeatable adult estimate when you can keep the method and measuring conditions consistent. The circumference method can be used without age; leaving age blank does not verify that the user is an adult. The BMI method requires a whole age from 18 to 80 under CalcBE’s product boundary.
- Choose one method and keep it for comparisons.
- Measure at the specified sex-specific locations.
- Read changes over time, not one result as a clinical verdict.
Methods, sources, and limitations
Both options are population equations, not direct measurements. The legacy circumference equation uses imperial coefficients documented in a 1999 U.S. Department of Defense report, based on 1984 Navy research. It is not the current official U.S. Navy BCA.
The Deurenberg adult equation was published in 1991. The study overall observed BMI values from 13.9 to 40.9 kg/m²; calculations outside that overall sample range are extrapolations. CalcBE applies the adult equation only for whole ages 18–80 as a product safety boundary.
The category bands are neutral general adult references with partial provenance. The supporting ACE page does not establish every boundary as one complete official table. The bands are non-diagnostic.
FAQ
Which formulas does this calculator use?
The circumference option uses legacy U.S. Navy/DoD equations: imperial coefficients documented in 1999 from research reported in 1984. The BMI option uses the 1991 Deurenberg adult equation. Results are validated rather than clipped to 0% or an arbitrary 75% ceiling.
Is this the current official U.S. Navy BCA?
No. The current June 2026 Guide-4 procedure uses height, waist at the navel and weight in a two-step process, with authorized measurements and PRIMS for official out-of-table results. This page implements a legacy circumference estimate.
Can children or teenagers use it?
The BMI option on this page is restricted to whole ages 18–80 and does not apply the adult equation to minors. The circumference equation does not use age, so an empty age field cannot verify adult status. Seek an age-appropriate professional reference for children and adolescents.
Why does the result differ from a smart scale, DEXA or another calculator?
Each method uses different measurements, models and assumptions. Hydration, tape placement, muscle mass, body shape and rounding also affect results. Compare the same method under similar conditions.
What does “outside the Deurenberg study sample” mean?
The original study overall observed BMI values from 13.9 to 40.9 kg/m². Outside that range the equation is being extrapolated, so the estimate may be less reliable; it is a warning, not a diagnosis.
How should I use the percentage over time?
Use repeated measurements under similar conditions to watch a trend. Do not treat one percentage or category as a diagnosis, a treatment target or an exact “true” body-fat value.