If there’s one thing for sure, that is that getting a good fitting cover for your futon mattress is critical for it not only looking its best, but functioning its best as well. So, what you need to do before buying that futon cover is to measure, measure, measure. If real estate is all about measuring, then getting a good fitting cover is about measuring. It may be helpful to pull the futon off the frame and lay in on the floor for a more accurate reading.

No matter how you do it, you need to ensure that you take into account the odd shape of the mattress. By odd, we mean to say that a futon has more rounded edges a unique profile that makes it a little trickier to measure accurately. You can think of it like a marshmallow rather than a cube. This rounded edge needs to be taken into account. When waterbeds were more popular than they are today, bed sheets were similar. The waterbed has a rounded edge as well.

In terms of sizing, keep these estimates in mind:
Twin: 39”x 75”
Full: 54”x 75”
Queen: 60”x 80”

With these in mind, finding the perfect fit is a matter of starting with these. Then, you’ll need to take into account the thickness of your mattress. There are thicknesses of up to 10”, so if you just quickly happen on a site that is showing the futon slipcovers you want but fail to read the details, you may end up with a cover that just doesn’t fit. Unless you don’t mind it not covering the sides of your entire mattress. However, this is not recommended.

You will also have to keep in mind that the material you choose will also play a role in determining how your mattress cover will ultimately fit. Having something that is made of cotton will tend to shrink. So, you can still wash it regularly but just make sure to remove it from the drier prior to it getting too small.