All Scarpa non-plastic footwear uses European sizing. • 1 Euro whole size = 6.6 mm = 0.26 inches • 1 US whole size = 8.4 mm = 0.33 inches • The 30 Euro sizes above cover the same size range as 24 US sizes. • More Euro sizes provide a better, more precise fit for your intended use. Rock Shoes: Scarpa recommends you downsize 1/2 to 2 full sizes from street shoe size, though downsizing depends on shoe model, intended use and personal preference. Mountaineering: Scarpa recommends you upsize 1/2 size or more depending on desired fit. Scarpa plastic mountaineering boots are based on the UK sizing scale. Ski Boots: All Scarpa ski bootsare measured in Mondo sizing. Highlighted (or not) sizes share the same shell size; the liners are lasted for each 1/2 size. Some skiers may want to downsize up to 1 full Mondo size, depending upon personal preference.