I definitely like having negative ease for the socks, which means I can’t use the suggested number of stitches following the directions in Sensational Knitted Socks, which don’t allow for any negative ease.

This is how I calculated the dimensions for my test sock, which I made from Cascade 220 Superwash (for faster results!):

My Foot:
9 3/4″ long from back of heel to toe
8 3/4″ foot circumference
8 1/2″ ankle circumference
2 1/4″ heel

I measured my foot length by standing against a wall with no floor molding and measuring from the wall to the tip of my toes. The foot circumference was while standing.

I wasn’t exactly sure how to mention the heel height, I think mine might be closer to 2 1/2″, but the chart in Sensational Knitted Socks said 2 1/4″ for my shoe size, and socks with that heel length seem to be fine with my shoes, so that’s what I’m going to call it.

Since my ankle measurement wasn’t that much less than my foot circumference, I just ignored it and went with the foot dimensions.

The math:

Since I was knitting a pattern stitch on the top half of the foot, I calculated the gauge for both stockinette and the pattern, and took the average. To get the gauge for the pattern stitch, I stretched the swatch out widthwise enough to flatten out the pattern, but not enough to distort the stitches. I guess that’s what they call “lightly stretched”. I came up with 6 stitches per inch for stockinette, and 5 stitches per inch for the pattern.

Then I took the stitches per inch times my foot circumference and averaged the two totals:

8.75 x 6 = 52.5
8.75 x 5 = 43.7

52.5 + 43.7 = 92.2
96.2 / 2 = 48.1

This matches the 48 stitches recommended for my size in the book (no negative ease). Then I calculated two figures - one at 10% less and one at 15% less:

48.1 - 10% = 43.3
48.1 - 15% = 40.9

So I figured my number of stitches to cast on should be 41 to 44. The closest match was 40 stitches for this pattern. That was slightly under my 15% calculation, but since the pattern was a stretchy rib, and it was less than one stitch off, I figured it would work out.

Finished measurements of my test sock:

10″ back of heel to toe
9 1/2″ sole of foot (heel turn to toe)
2 1/4″ heel flap
6″ leg (I deliberately went a bit short)
6 1/2″ circumference unstretched

The circumference seems small looking at the unstretched dimension, but it has a rib pattern over the instep, so it stretches quite a bit and fits well. I was actually shooting for 9 3/4 in foot length, but the toe came out slightly longer than I expected. Interestingly enough, I found that the slight extra length isn’t really a problem since I have a lot of negative ease in the circumference, so I didn’t bother to reknit it. But I think I’ll still try to knit the next pair of socks to a total length of 9 3/4″ to match my foot.

The leg length was “adequate”, but I’d prefer 7″. I only did 6″ because I wasn’t sure if there’d be enough yarn for both socks.

I’m happy with how it turned out, so I think I’ll keep using this calculation. I’m sure that once I get more experienced, I’ll have a pretty good idea of what number of stitches is appropriate for a certain weight of yarn, but at least I have a place to start.