This will depend on how you like your bed. As a guide we suggest 6-8 bags to start a 12ft x 12ft stable. If you like banks then 10 may be needed. Pellet bed can be slightly more expensive to set up but due to the clumping and quick absorption the waste will be far less and you will save money on the regular up keep.
Some of our customers are using pellet bed on its own, others are using it on top of rubber matting, some are using it as a cushioning absorbent base with straw on top. It is a very versatile bedding option.