body fat calculator
Estimate body-fat percentage from tape measurements with the US Navy circumference method. A rough proxy beside calipers or a scan, and marked as one.
Just below the larynx, tape sloping slightly down at the front.
At the navel, relaxed, not sucked in.
Add it to split the estimate into fat mass and lean mass.
A tape estimate is a rough proxy beside calipers in practiced hands or a DEXA scan. Its virtue is repeatability: same tape, same landmarks, same morning. Trend the number rather than trusting any single reading; the platform treats body-fat readings exactly the same way.
the estimate is only as good as the tape work.
The Navy method reads three or four circumferences and nothing else, so how you take them is the whole game. Same tape, same landmarks, same time of day, and the reading becomes repeatable enough to trend.
| where | how | |
|---|---|---|
| neck | just below the larynx | tape sloping slightly down at the front, snug but not compressing |
| waist | men at the navel; women at the narrowest point | relaxed and breathing out normally, never sucked in |
| hip (women) | at the widest point | feet together, tape level all the way round |
| every reading | the same landmarks each time | same morning, before food, twice, and average |
trend the estimate, never worship a reading.
Every body-fat method is an estimate, from a bathroom scale's bioimpedance up to a DEXA scan; they differ in how wrong they are, not whether. The honest way to use a rough method is the way the platform uses every reading: mark it as an estimate, take it consistently, and read the line, not the point.
See how the two masses this estimate implies are tracked over months on the recomposition page, and how the scale itself is kept honest on the honest scale.
the honest answers.
How accurate is the Navy tape method?
Rough, and honestly so. Against a lab reference it commonly lands within a few percentage points, sometimes more on very lean or very muscular bodies. Its real strength is repeatability: the same tape at the same landmarks drifts far less than the method's absolute error, so the trend it draws is worth more than any single reading.
Should I use a tape, calipers, or a scan?
Whichever you will actually repeat. A DEXA scan is the tightest single reading and the least repeatable weekly habit; calipers are good in practiced hands and noisy in new ones; the tape is the roughest and the easiest to repeat identically. For tracking change, consistency of method beats precision of method.
Why does the calculator split fat mass from lean mass?
Because the percentage is not really the point. Recomposition is lean mass rising while fat mass falls, and the scale weight that hides both. Splitting your weight into the two masses is exactly what the platform tracks over time, on one honest scale.
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- protein calculatorA daily protein range by goal, never a false-precision decimal.
- calorie deficit calculatorAn intake target and an honest weekly rate; below-BMR plans are refused.
a calculator estimates once. the platform watches what actually happens.
Every number this page gives you is a starting point. Trainbase is where a coach and a client watch the real ones move: every set logged against a program, every reading on one honest scale, every estimate marked as an estimate. When the trend disagrees with the calculator, the trend wins.