Each shell size includes half sizes. i.e. 26.0 and 26.5 use the same shell. The G-Fit 2 liners can be baked and tend to pack out. Be cautious in going too small. Unlike downhill boots, you walk in these including jabbing your foot into boot pack climbs and downhill walking. If the boots are too short, you will be injured and cold. Shell fit is most important because the liner can be stretched and formed. You really want some room in the shell but not more than 2-fingers. I am 1-1/2 sizes smaller than street shoes in alpine boot performance fit, and 1/2 size smaller for the Garmont Adrenalin.