What size laying boxes should i have ?

[RicksKickinChicken]

i bought some biddies from a feed store and they said there were all rhode island reds but i think some look more like the new hampshire red but anyway they are the same size if that helps. im building a coop for them with laying boxes how wide or tall should i make them? or how little can i make them since im making them on such a tight budget.

 

[gryeyes]

Minimum size 12 inches by 12 inches, and 15 inches deep.