Body Fat % Calculator (Navy Method)
Estimate body fat percentage using the US Navy tape method.
What is the Body Fat % Calculator (Navy Method)?
A body fat percentage calculator using the US Navy method estimates body fat from a handful of circumference measurements, without needing specialist equipment. It works using the Navy's regression formula, which for men uses height, neck and waist measurements, and for women adds a hip measurement, applying different logarithmic coefficients for each sex to convert the measurement ratios into an estimated body fat percentage. To take the measurements accurately: measure your neck just below the larynx and your waist at the navel (and hips at their widest point for women), all in centimetres or inches consistently, then apply the Navy formula — this circumference-based method is a widely used field estimate but is less accurate than DEXA scanning or hydrostatic (underwater) weighing.
How it works
The US Navy method estimates body fat percentage from a small set of circumference measurements (neck, waist, and for women, hip) combined with height, using a formula developed and validated for military fitness assessment. It's a logarithmic formula — the relationships between the measurements and body fat aren't simple linear ones, which is why the calculation looks more complex than a straightforward ratio.
UK context
This method is popular because it requires nothing more than a measuring tape, unlike more accurate methods such as DEXA scanning or hydrostatic (underwater) weighing, which need specialist equipment. It's reasonably reliable for tracking your own trend over time if you measure consistently, but it's less accurate as an absolute figure than lab-based methods.
Tips
- Measure waist at the navel and neck just below the larynx (Adam's apple) for the standard, validated measurement points — measuring at different points will skew the result.
- Take measurements at a consistent time of day (many people find first thing in the morning most consistent) for the most reliable tracking over time.
- Because this method uses circumference rather than direct fat measurement, it can be less accurate for people with unusual body composition or fat distribution — treat it as a useful estimate, not a precise diagnosis.
Frequently asked questions
How accurate is the Navy body fat method?
It's a widely used, reasonably reliable field estimate for tracking trends, but it's less accurate as an absolute figure than lab methods like DEXA scanning or hydrostatic weighing, since it estimates from circumference measurements rather than measuring fat directly.
Where exactly should I measure my waist and neck?
Waist is measured at the navel, and neck is measured just below the larynx (Adam's apple) — using consistent measurement points each time is important for reliable tracking.
A quick note
Uses the US Navy circumference method, a widely used field estimate — less accurate than DEXA or hydrostatic weighing. Not a substitute for professional body composition assessment.