15" works. That will fit a standard can or two narrow cans.

My trash cans are 15", and they sit in 16.5" pull-outs. The cabinet front is slightly bigger. I love them!

For both the OP and those who answered - when you give a 15" size, are you referring to the opening clearance or the cabinet width? Wouldn't a framed cabinet lose 1 1/2" from each side due to the frame, so that the opening on a 15" cabinet would be 12"?

I looked at the specs for Kraftmaid which is a typical 3" increment semi-custom framed cabinet line, and they offer two base cabinets that are 15" wide. One holds a single 35 quart can with the narrow end facing the front, and one holds two smaller squarish cans, one behind the other.

Their 18" cabinet holds two 35 quart cans front to back with the wide side facing front.

The 15" and the 18" are the actual cabinet widths.

The OP did state "recycling," so I assume two cans in the cabinet holder. I just measured mine again, and the can's are 15", but the door is 18". We are a family of two. For a family of four, you will need to assign one kid the task of emptying the trash because it will need to be emptied more often if your door is 15".

We have a 15" wide trash/recycling pullout (frameless, under our sink) for our family of four. Fits two 13-gallon cans, one for recycling and one for trash. Works well for us! I think you would have to go down to a single can for a 12" wide cabinet.

Instead of looking at the size of the cabinet, look at the size of the cans it holds. If they are smaller than they could be, consider ordering a cabinet and retrofitting your own hardware.

I installed this in my dear departed kitchen: http://www.amazon.com/gp/product/B000PGVJUO/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

It went into a 12" opening, two cans, 27 qts. each. It was a tiny bit small for the 4 of us but not by much. Anything bigger would be great.