If you have decided to use a corner bookcase, start in the corner & measure your wall out to your stopping point. This gives you a wall length.
Our corner bookcases are offered in 2-down the wall depths which are 25 & 29.25.
Take your total wall length & subtract either 25 or 29.75. The number left is the length of bookcases you need to cover your wall.
If your wall lengths are not the same repeat this procedure for the second wall.
Pictured are two-36x84x12 bookcases & one-25″down the wall corner bookcase. Your wall needs to be at least a 61″length for these to fit.