What size do women prefer?
In the best study (3D models, Prause 2015), women preferred about 16 cm (6.3 in) length and 12.2 cm (4.8 in) girth for a long-term partner — slightly above average, with girth mattering as much as length.
Asked to pick a long-term partner, women in the best-run study chose about 16.0 cm (6.3 in) in length and 12.2 cm (4.8 in) in girth — barely above average. What makes Prause et al. (2015) worth citing over the usual survey is the method: women handled 33 3D-printed models and picked one, instead of pulling a number out of memory or fantasy. Tactile beats hypothetical.
The preferred size shifts with context, but not much. For a one-night partner the choice crept up to 16.3 cm length and 12.7 cm girth; for someone to keep around, it drifted back toward the mean. Girth carried as much weight as length in both cases — no surprise, since the nerve endings that register it sit in the outer third.
The number men tend to miss is the satisfaction one: in survey after survey, the large majority of women say they’re happy with their partner’s size — a far bigger share than the men happy with their own. The deficit is mostly self-inflicted.
More in does size matter.