Hi this is Jon on behalf of Expert Village in this video clip we would be laying out our shelves. Since we made each opening of our project the exact same size our shelves are all going to be the same in width. As I measure that opening I get 21 13/16 however I want to leave my shelf with just a little bit of room to play cause I don't want them to fit in so thigh they might warp out one of the sides. So I'm going to take off a little bit of this measurement. Now the depth is going to be the same as my inner partitions cause I am going to put that 1/4 inch of plywood on the back I need it to sit in just a 1/4 inch. So my measurement would be 9 3/4. Now I'm going to be putting trim across the front of all of my shelves so I'm going to subtract off that 3/4 which gives me a overall measurement of 21 3/4 x 9 for my plywood. If I take a look back at my drawing I have 3 shelves on each of the outside and one in the center for a total of 7 shelves. Now looking at the back of my unit my doors fit inside so my shelf inside of here is actually going to be a little bit smaller so I'm going to measure from the inside of that door out to my outside piece and I get 9 inches. So for that one inside shelf my measurement was 21 3/4 x 9 but I need to subtract 3/4 for trim which gives me a overall of 21 3/4 x 8 1/4 and I just need on of those.