Is 5 inches below average?
Barely. 5 inches (12.7 cm) is about 0.4 cm under the 13.12 cm average — roughly the 40th percentile, well inside the normal range.
Technically yes, but only just — and it doesn’t matter. Five inches is 12.7 cm; the average erect length is 13.12 cm (5.16 in). That’s a gap of about 0.4 cm, or a quarter of one standard deviation. On the bell curve, 5 inches sits near the 40th percentile, meaning roughly four in ten men are shorter than you.
To put 0.4 cm in perspective: that’s the thickness of a few stacked coins, and smaller than the error you’d introduce by not pressing the ruler to the pubic bone. Sloppy technique can move your result by more than the gap you’re worried about.
Five inches is firmly inside the normal range (about 90% of men fall between 10.4 and 15.9 cm erect) and more than 3 cm above the clinical micropenis threshold (~9.3 cm). It’s a textbook-ordinary number.
More in is 5 inches normal.