Navy Body Fat Calculator (Circumference / Tape Method)
Estimate your body fat from height, neck and waist using the U.S. Navy tape method — no calipers, no scale. The Navy method is pre-selected below.
Calculate Body Fat %
Required: the body-fat formulas use biological sex (male or female) as a variable, so the estimate can’t be calculated without it.
Optional — the Navy formula doesn’t use age, but it lets us flag results for under-19s, whose healthy body-fat ranges differ during growth.
Enter your height in centimeters (e.g., 170 cm)
*This calculator is for informational purposes only. Please consult a healthcare professional before making any health decisions. See our medical disclaimer for more information.
Calculations are powered by the US Navy Circumference Method (Hodgdon & Beckett, 1984), the US Department of Defense field method for body-fat estimation, derived by Hodgdon & Beckett at the Naval Health Research Center (Reports 84-11 & 84-29) and documented and cross-validated in the National Academies review Body Composition and Physical Performance (1990).
Quick Answer
The Navy Circumference Method
The U.S. Navy method estimates body fat from just three tape measurements — height, neck and waist (plus hip for women). No calipers and no scale are needed. As a worked example, a man of 178 cm with a 38 cm neck and a 90 cm waist lands at about 20.1% body fat. Enter your own numbers in the calculator above, which is pre-set to the Navy method.
What the Navy Method Actually Measures
The circumference method — developed by Hodgdon and Beckett for the U.S. Department of Defense — works because the ratio between your waist and neck tracks how much fat you carry around your midsection, and height scales that against your overall size. It does not weigh your fat directly; it estimates the percentage from the proportions of your body. That is why the same waist reading gives a lower body-fat figure on a taller frame, and why the equation is sex-specific: men use neck and waist, women add the hip.
How to Take the Three Measurements
Measure your neck just below the larynx, with the tape sloping slightly down to the front. Measure the waist horizontally — for men at the level of the navel, for women at the narrowest point. Women also measure the hip at the widest point of the buttocks. Keep the tape snug but not compressing the skin, breathe normally, and take each reading in the morning before eating for consistency. Because the estimate depends entirely on these three numbers, measuring at the same time of day each week is what makes the trend meaningful.
Reading the Fat-Mass and Lean-Mass Split
Once you add your weight, the tool multiplies it by your body-fat percentage to split your body into fat mass and lean mass. For an 80 kg man at 20.1%, that is about 16.1 kg of fat and 63.9 kg of lean mass. The calculator also places your figure against the American Council on Exercise (ACE) reference bands — essential, athletes, fitness, acceptable — which are shown for context only, not as a target to hit.
Where the Estimate Drifts
A tape-based estimate assumes an average build. Very muscular people, or those who carry weight differently from the military populations the formula was fitted on, can read a little high or low. If your Navy figure looks off, cross-check it against the BMI method on the same tool, and confirm your lean mass with the Lean Body Mass Calculator. To feed that composition into a resting-calorie estimate, the Katch-McArdle Calculator uses your lean mass directly. For both methods side by side, use the full Body Fat Percentage Calculator.
The circumference equation is the U.S. Navy method (Hodgdon & Beckett, 1984). It is a field estimate with a typical margin of a few percentage points — useful for tracking change over time, not a lab measurement.
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