Floating shelf weight rating
I can't seem to find a hard answer on this so I'll gather opinions here.
I want to make floating shelves in a room of mine; there will be 4 separate corner pieces (it will circle the room aside from windows and door frames). I think I'm going to go with a ladder support system as that seems stout and is easy. I'll either make the shelf outer from pine boards or plywood and rip to size. I may rout the edges, or leave square (still unknown).
I was going to make the ladder support from 2x6s that I'll rip to 2x3s (more consistent size and shape vs 2x4s at my local store). These will of course be screwed (or lag bolted) into studs at every opportunity. Shelf will stick out 12". It's fore small kitchen appliances, plates and bowls, etc.
Is there some formula for structural wood to calculate this? I'd be happy if each 16" wide piece of shelf would support 50 lbs, aside from shelf weight.