I have about the same size feet as you. Measure US 13 and wear 13 or 14 (47 or 48 euro size) shoes/boots. For me, 48 is big enough, and that's the size of my Garmont summer mountaineering boots which accept semi-auto. For ski boots I'm in size 28-30. Works for me, but definitely need some punches or shell molding in the smaller size resort ski boots!