Shelf support - which way round?

[Lusi83]

Ok stupid question time
I want to put a shelf up with the cheap white metal angle shelf supports...

Just realised that the arms of the supports are different lengths - one support one arm is 6inch long and the other arm is 5 inch ...

So do you fix the longer arm to the shelf or the wall? Does it matter?

(I have already put a bigger shelf up with the longer arms into the wall -thought the shelf now seemed a bit wide for the bracket! - I thought they were the same length so lucky they are the same way cos it could have been a mixture! )

 

[big-all]

long arm on the wall with the shelve 20 to 35% bigger than the bracket dependent on material and load

 

[Lusi83]

Thanks! Small shelf will be fine but the bigger one I think I might have to make a bit narrower....
Held the bracket to it and it looked right (must have been the longer arm...) but now it doesn't look quite right

 

[big-all]

whats going on the shelves how far apart are the brackets and what material are the shelves made from