Coroplast SIZE.?!?!

You need to decide what height you want the sides to be, how long of a ramp you want and how wide you want it to be. You might want to look at the photo section to get ideas of what you want it to look like. Then you can calculate how much you need.

The biggest problem (other than cutting it) that I've had with coroplast is figuring out how to make it fit inside my cage. A lot depends on whether you are using those connectors (plastic knob things) and where you are using them. If they form the base of the loft, or part of the sides, then the coro needs to be cut a bit smaller to clear them. Also, if you are using them, then your grids have a gap, which adds to their dimensions. The most accurate way to measure might be to assemble the loft (not on your cage) and then take the inside measurements? And remember to add the sides all the way around the loft.

I'd construct the grids first and then measure the inside, allowing for the overlapped sides of the coroplast.