Use a tape measure and the US Navy formula, then cross-check against a visual guide. You only need your neck, waist and height (plus hips for women). It's typically within a few percentage points of a lab scan, which is plenty for tracking progress. When you're unsure, round up: most people underestimate.
Men: 86.010 x log10(waist - neck) - 70.041 x log10(height) + 36.76
Women: 163.205 x log10(waist + hips - neck) - 97.684 x log10(height) - 78.387
Example (man): 70 in tall, 15 in neck, 34 in waist.
86.010 x log10(19) - 70.041 x log10(70) + 36.76
= 109.99 - 129.23 + 36.76 = 17.5% body fat
Match yourself to the closest description. This is the same guide built into the Physique Score.
| Men | Women | What it looks like |
|---|---|---|
| 6-9% | 14-17% | Stage-lean: deep abs, vascular, muscle separation. Very hard to hold. |
| 10-12% | 18-20% | Clear abs and definition; athletic |
| 13-15% | 21-24% | Abs visible in good light, or faint; fit look |
| 16-19% | 25-29% | Flat or smooth stomach, no visible abs |
| 20-24% | 30-34% | Noticeable belly or fuller hips and thighs; softer midsection |
| 25%+ | 35%+ | Rounder overall, little definition |
One more quick check: if your waist is under 0.45 of your height and you can see abs in decent light, you're most likely in the low-to-mid teens (men) or low 20s (women).
It's typically within a few percentage points of a lab scan. It's best for tracking change over time: measure the same way, at the same time of day, every few weeks.
Roughly, yes. Compare yourself to a visual guide in even lighting. Use it as a cross-check with the tape measure rather than on its own, and round up when unsure.
Body fat sits mostly on the waist, so it changes every waist-based ratio. It's also needed to calculate your FFMI, which measures muscle for your height.
Enter your body fat in the Physique Score to get your FFMI and conditioning grade. Free, no login needed.