I have size 11.5 us shoes, what size snow board boots would i need and what size bindings?

For boots, probably 11 or 11.5, U NEVER KNOW though, deffinatley try and buy boats at a local boarding shop or sporting goods store where you can try them on and get a feel for them. DONT buy boots online! As for bindings, no question about it, Deffinitley LARGE

Usually Snowboard boots have the same sizes as the street shoes you are wearing, upsizing is not usual, in most case you would want to down size but just to be sure order your exact size or try the boot on first before buying

Get a 11 or 10.5 its going to be a little uncomfortable at first but the more you wear them the more your boots are going to pack out "get streched out" you want them to fit snuggly. go try a bunch on. every boot feels diffrent. youll want a large binding. med.s would probably be too small. if you buy your boots and bindings at the same time while wearing you boot strap into one of the bindings to see if they mesh well. each comapny designs there equpiment to preform the best when used with the same equipement. so to maximize your preformace get the same brand boots and bindings but its really not that big of a deal