There has been the occasional misconception that The Sock Ruler® equates to the foot's actual length, which it does not. It was not designed to measure the length of a person's foot, although it is helpful to have that information when you knit a sock. Some people have asked me about knitting for a man who wears a size 14 shoe, for example. That man's foot length is probably 12". The toe decrease would typically begin two inches before the end of the sock. For a 12" foot that toe decrease would start at 10" which is the length of the ruler. After you start the toe decrease you no longer need to use The Sock Ruler®. Please refer to the Shoe Size Conversion Chart should you need help determining the length of the foot of the sock.
The Sock Ruler® fits inside of the sock for measuring. This picture shows the sock leg knitted to 7.5", the start point for the heel flap.
The heel flap has been knitted 1.5 inches since the previous measurement of 7.5 inches.
The heel has been turned and The Sock Ruler is tucked into the heel, and shows that the foot has been knitted to 4.5 inches. When it has been knit to 8 inches I will start the toe shaping.
Sock pattern, Wavy Basketweave, used with permission of the designer, Gregory Courtney of Tutto, Santa Fe, NM.