Skiers use the Mondopoint sizing system to determine the correct fit for their ski boots. Due to the international nature of the ski industry, the Mondopoint system was put into place in order to make ski sizes universal. While the Mondopoint system appears to vary greatly from the usual American shoe sizing system, converting your shoe size to the Mondopoint system only requires a one-step calculation.
Figure out your normal shoe size. If you do not know your shoe size or your shoe size varies greatly from shoe to shoe, you may wish to visit a shoe store and have your foot measured by a professional. For example, imagine that your shoe size is a men's 11.
Determine the number that you need to add to your normal shoe size to get your Mondopoint. For men's shoes, add 18 to your normal size; for women's shoes, add 19 to your normal size. In this example, you would add 18 to 11.
Change your shoe size units to Mondopoint. In the example, your Mondopoint size would be 29.