Fitting socks is a bit easier than fitting sweaters, you mainly have to worry about the length of your foot and the circumference of you foot and/or ankle. Most of my sock books recommend about 10% negative ease for the sock circumference and 1/2″ of negative ease for sock length.
Here’s how I found the ideal sock dimensions for my foot. First I measured around the widest part of my foot just below my toes. On me, this measurement is just shy of 9″. On my calculator I put in my foot measurement times .9 and pressed the equals key. (9 x .9 = 8.1) My idea sock circumference would be around 8″. Why multiply by .9 you might ask? To make a tube 10% smaller than my actual foot circumference, I need 9/10 of the total size. Multiplying by .9 gives me an answer that is 9/10 the original number. Since my foot is really just shy of 9″, I rounded my answer down.
Length is a bit easier. I measured my foot length while standing and subtract 1/2″. My foot length is 9 1/2″. 9 1/2″ – 1/2″ = 9″ So I need a 9″ foot length on my socks.
All this works great as long as you are getting the gauge listed in the pattern. I always swatch in the round when making a gauge swatch for socks. I usually cast on the number of stitches in 4″ in a tube and knit in the round for an inch or two. I then measure across the tube. If it is 2″ across, I’m getting gauge. If not, I do a purl row and switch needles and try for another inch or two. If the tube is too large, I try smaller needles, if the tube is too small, I try larger needles.
For my last pair of socks, I simply could not get the row gauge listed in the pattern. It called for 34 stitches over 4″ (or 8.5 stitches an inch) and even on my smallest needles, I could only get 32 stitches over 4″ (or 8 stitches an inch). So I multiplied my gauge per inch by my ideal sock circumference (8 stitches x 8″ = 64) and I picked the sock size in the pattern that used 64 stitches– in my case, my pattern had a size that used that exact amount, but you may need to pick a size with a few less stitches than your ideal. I then went through the pattern circled the numbers for the 64 stitch size for anything that was about sock circumference and I circled the numbers for my “real” size (as if I were getting gauge) for any directions having to do with length. That way I was able to make a sock that fit!
(Most sock patterns use measurements, not row counts, for directions having to do with length. If my pattern had included row counts, I would have needed to check my row gauge and adjust those as well, but in sock patterns this is not at all common.)
Of course, if you just enjoy making socks, every pair you make will probably fit somebody! Here’s a pair that I though I was making for myself but they turned out the perfect size for my husband!