There is much confusion over knitting needle sizes, especially when using old patterns that reference older US or UK needle sizes, or when trying to convert between US and metric needles, or use older needles with newer patterns (although a needle gauge is recommended for this purpose). Of course you should always swatch when choosing the correct needle but the following chart is useful in providing a starting point. Some of the old needle sizes are no longer represented, for these choose the nearest new needle size.