<P> In North America, there are different systems that are used concurrently . The size indications are usually similar but not exactly equivalent especially with athletic shoes at extreme sizes . The most common is the customary, described in more detail below, which for men's shoes is one barleycorn shorter than the UK equivalent . (so a men's 13 in the US or Canada is the same size as a men's 12 in the UK) </P> <P> The traditional system is similar to English sizes but start counting at one rather than zero, so equivalent sizes are one greater . So the calculation for a male shoe size in the USA or Canada is: </P> <Dl> <Dd> male shoe size = 3 × last length in inches − 24 (\ displaystyle (\ mbox (male shoe size)) = 3 \ times (\ mbox (last length in inches)) - 24) </Dd> </Dl> <Dd> male shoe size = 3 × last length in inches − 24 (\ displaystyle (\ mbox (male shoe size)) = 3 \ times (\ mbox (last length in inches)) - 24) </Dd>

What do the letters mean in shoes sizes