Measurement Tracking Sheet

Baseline

Date

Formula used

Height (in)

Weight (lb)

Neck

Waist

Hip (women)

BODY FAT %

Fat mass

Lean mass

Track it monthly — three readings each, averaged

The formulas and the sites

Men

86.010·log₁₀(waist−neck) − 70.041·log₁₀(height) + 36.76

Women

163.205·log₁₀(waist+hip−neck) − 97.684·log₁₀(height) − 78.387

⚠ UNITS

INCHES — the metric form has different constants

⚠ If a source says cm

with THESE constants, it is wrong

Neck

below the larynx, sloping down at the front, unflexed

Waist — MEN

at the navel

Waist — WOMEN

narrowest point, usually ABOVE the navel

Hip

widest point, feet together

When

end of a normal exhale, tape snug not tight

Half-inch waist error

≈1 pp (men) · ≈0.65 pp (women)

Source

Hodgdon-Beckett, Naval Health Research Center, 1984

Getting a number worth comparing

• Measuring in INCHES
• Same tape every time
• Same time of day — morning, before eating
• Three readings per site, averaged
• Waist at the correct site for the formula you are using
• Not flexing, not holding breath, not pulling the tape tight
• Weight recorded at the same time
• Comparing against your own last reading, not against a chart

The units trap

These constants are for inches. A separate metric version exists with completely different ones. Push centimetres through the inch formula and it returns a plausible wrong answer — 26.7% for a body that is 20.1%. Nothing errors, nothing looks odd, and the number is six points out.

Track the trend, not the digit

If it says 22% it might really be 19 or 25. But if it says 22 in March and 19 in June, measured the same way both times, something real changed. This is an instrument for detecting change, not a verdict — which is also why measuring technique matters more than the formula does.