I finally decided to do the virtuous thing. I decided it would be way less wasteful to swatch than it would be to pick a random number of stitches, cross my fingers that the sock would fit, spend a lot of time pretending everything was fine until the first try-on revealed the (obvious) fact that it was entirely too small. So I swatched AND I measured my leg.
The Knit Picks pre-dyed gave me 8.25 stitches/inch on size 2s after blocking, and my none-too-large leg is 11 inches around at mid-calf.
But I don't know how many stitches I should cast on as a result. It turns out knowing my gauge in advance is not helpful to me in the slightest because I don’t know how much “give” to expect from sock yarn.
I see a lot of sock patterns that start with 64 stitches. It can’t possibly be that I need to cast on 80+ stitches, can it? My legs are on the skinny side and unless every other sock knitter in the world is a willowy-legged midget, I imagine I need to factor in some stretch.
Other sock knitters, please advise?