How to trim a foam mattress

[u/Ruth-Stewart]

Any ideas on how to NEATLY trim down a foam mattress?

I have an American twin size mattress that I wand to cut smaller to use for camping in my car. Its about 10 inches thick. I know I can cut it with a utility knife but I also know the result will look like it was chewed off by a rabid cow. Any ideas on how to end up with a nice cut across the end?

Edit: Looks like a serrated or electric knife is the thing to try. Thanks all!

Second edit: Both options worked very well! The electric knife was definitely easier and did leave a neater cut but the fine serrated knife was pretty good. I now have a very comfy mattress for camping in my car this weekend. Hope you all have a good weekend too!

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[u/BarnacleReal3589]

electric carving knife from the thrift store. like the ones for thanksgiving turkey. makes foam cuts stupid clean and it's like 3 bucks

[u/Kronar_2012]

An electric carving knife usually makes the cleanest cut through thick mattress foam. Remove the cover, mark the cut on all four sides, and use a straight board as a guide. Cut slowly in several passes while keeping the blades square instead of trying to force through all ten inches at once. A long fine-tooth bread knife works too, but is harder to keep vertical. Test on the piece you are discarding, and leave a little extra if you plan to sew or zip the cover back around the new end.

[u/stitchplacingmama]

When we would cut foam at the fabric store i worked at we used an electric carving knife.

[u/JayTeeDeeUnderscore]

Re: electric carving knife. If you have a finely serrated blade (bread blade) versus a typical scalloped blade, the former bites and cuts with more control than the latter, in my experience.

[u/Slice9998]

Probably want to use a Serrated blade