This sock ruler is so handy. It rolls up to store away in your notions bag or wear it around your wrist while you work.
No math required to use it, just knit until you reach your size. You can knit for anyone without getting their measurements. All you need is their shoe size. It works for Top Down or Toe Up socks equally well.
The rulers have both inches and centimeters. Shoe sizing uses American sizes.
