Ski boots are not sized using traditional US sizing most of us are used to. Ski manufacturers use a sizing system known as Mondo Point to size boots in a universal measuring system. Mondo Point is a European measurement for shoe sizes that is measured in centimeters. To determine US sizing from Mondo Point, simply add the first and second digits together, and then add the decimal point (you will need to add 1 to your calculated result to convert a US men's size to w women's size). For example, a boot that is sized as a Mondo Point 29.0 would be calculated as 2 + 9 + .0 = 11.0. Thus a Mondo Point 29.0 is a men's 11.0. One special point of note here, once you reach a Mondo Point size 30.0, this calculation will begin to fall apart unless you alter your formula to add 9 to the result. For example, a Mondo Point 31.5 would need to be calculated as follows: (3 + 1 + .5) + 9 = 13.5. Without the addition of 9, your calculation would end up as 4.5, which would definitely be too small for an individual looking for a 13.5.