A sock ruler 101, useful for knitting socks and other garments, features a curved heel section 120 that includes an apex 123 and two termination points 125 that are connected to a straight section 130. The straight section ends at a flat end section 190. Distance markings 110 may be found and spaced along the lengthwise portion 113, while the distance markings are written across the width 115 of the sock ruler. The curved heel section has a concave shape useful in knitting classical sock components such as sock cuffs 210 and sock heel flaps 230. The curved heel section allows the sock ruler to stay within a sock during sock knitting, making the distance markings readily available.