CSM Foot Calculator

I created a calculator to help figure out how many rounds to knit for the foot after finishing the heel and before starting the toe for a CSM sock.

For the best results, knit a sample tube (you can later rip it out and reuse the yarn). This tube should be knit with the desired yarn at the tension you have determined is best for it, with the cylinder on which you are making the sock, and you have created a fabric you think will fit the foot circumference you want. Use a washed sample or at least let it relax off the machine for a while before counting rounds (rows) .

Measure the foot or look up what the foot length is by shoe size. (I use this chart.) Count the number of rounds (rows) you get in 3 inches and divide that by 3 for the average rounds per inch (RPI).

Input your numbers into the fields below where there is an asterisk. There is instructions included with the fields you need to input.

This calculator works for me, I make no guarantees, I just offer it as a tool. Remember, socks don’t have to be exact; knitting stretches a bit when it needs to and it will fit a range of sizes, so you just need a number to get you in the ballpark for the desired foot size.

8 Replies to “CSM Foot Calculator”

  1. Thank you so much! I spent several hours tonight trying to develop this formula and finally put it aside to try to sleep on it. I am so relieved that you have already done that work for me.

  2. Sooooooo I didn’t swatch with Lycra. Wrong move since I used it for my sock. Love this though. Thank you!

    1. I don’t use Lycra, So I can’t really say how you might adjust for using it. You might have to plan for a smudge of positive ease when using Lycra.

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