How To Cut Foam Mattress?

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I have excellent news for you if you want to repurpose your old memory foam mattress or if you need to attain specified dimensions:

You can simply cut a memory foam mattress at home using equipment you presumably already have.

So, let’s discover how to customize your old foam mattress to new proportions and make it properly meet your demands.

What Knife Is Best for Cutting a Memory Foam Mattress?

This material is particularly pliant when it comes to memory foam.

As a result, you won’t require any heavy-duty equipment.

A knife would suffice, but not just any knife.

The following are the most frequent kinds of memory foam mattress-cutting tools:

#1. Electric knife

This is probably the simplest to use.

You won’t have to exert much effort, just slip the knife into the foam.

Furthermore, utilizing an electric knife is the most likely to produce sharp, clean edges.

#2. Carving knife

A long, sharp carving knife is another viable choice.

To cut through the foam with this knife, make quick back-and-forth strokes.

#3. Craft (utility) knife

These knives are usually sharp enough to cut through the foam.

Furthermore, they generally have a sharp tip that makes it simpler to read the information.

In this scenario, though, you should avoid sawing movements.

Instead, begin with a shallow incision on a tiny portion of foam and progressively deepen the cut until you reach the bottom and cut through the foam.

You may then go to the next phase.

#4. Extra-large scissors

You may also use heavy-duty scissors if you don’t have an appropriate knife (or if yours isn’t sharp enough).

For a smoother finish, cut smaller pieces of foam and use just the tip of the scissors (and more precision).

#5. Long serrated bread knife

A bread knife, if sharp enough, may readily cut through memory foam.

To cut through the material, you’ll need to employ sawing movements.

The edges may get ragged, but that shouldn’t be a problem if you intend to cover your mattress with a cloth cover.

Other Equipment Required

So, if you have purchased the greatest memory foam mattress and do not want to part with it, a few easy tools may assist you in transforming it into something new (like an RV mattress, for example).

Here’s what you may require:

  • A ruler or measuring tape (for taking measurements);
  • A sharpie (to draw the lines where you will cut your foam mattress);
  • A seam ripper (if the mattress cover cannot be removed);
  • A sewing kit (for customizing the mattress cover to the new measurements);
  • A square of drywall or a piece of plywood/hardboard (to help you cut the mattress in a straight line and be more precise).

How to Cut a Memory Foam Mattress to the Size You Want

When you have all of your supplies together, you may begin cutting your mattress.

But first, a word of caution: if you wish to cut a memory foam mattress, you must first determine if it includes fiberglass.

If it happens and you begin to cut, fiberglass particles will be spilled into the room.

And, to put it mildly, this may have extremely unpleasant repercussions (which may even harm your health) (1).

To determine if your mattress includes fiberglass, check the description online or contact the business from where you purchased it.

If you discover that your mattress contains fiberglass, cutting it is not an option.

And maybe in the future, you’d want to think about one of the greatest memory foam mattresses without fiberglass.

And if your mattress is safe to cut, these are the procedures you should take:

#1. Remove the mattress cover

If your mattress isn’t detachable, use a seam ripper to “open” it up.

#2. Put your mattress on a solid surface

You may protect your floor by putting a piece of plywood below it in case your knife cuts through it.

If the mattress is thin and light, you may wish to secure it by placing something heavy on the corners (like a couple of books, for example).

They don’t have to be very hefty (to avoid injuring the foam), just heavy enough to keep the mattress from slipping off.

#3. Determine the measurements of the mattress you want

Measure it, note the size, and use a sharpie or a marker pen to draw the lines according to the new dimensions.

#4. Without compressing the foam, cut the mattress

Keep in mind that the lower portion of the foam may be denser, which means you may have to use more effort to reach it.

To prevent warping the mattress, use a drywall square (or a piece of plywood) when working with softer foams.

#5. Trim off the excess bits

If the foam edges become ragged, trim away the excess.

You may cut it with scissors or a little knife.

#6. The fabric should be used to cover your “new” mattress

That’s where having a sewing kit comes in useful.

If you don’t want to sew, you may use safety pins instead.

Simply pull the cover close against the mattress, fold the extra fabric, and pin it all together (being careful not to damage the foam).

How to Horizontally Cut a Memory Foam Mattress?

You may make your memory foam mattress thinner by cutting it horizontally.

Let me warn you straight away: cutting a foam mattress horizontally may be challenging.

Precision is required, as are unique tools.

You now have a few possibilities.

A long horizontal saw is the most popular.

Hold the top piece of the foam but do not push too hard on it while slowly sliding the saw through the material.

As some foam particles may fly about throughout the procedure, it’s a good idea to place your mattress on a sheet or towel.

The cloth under the mattress will trap them, making cleaning much simpler for you.

Some users point out that if you have an electric saw, you can also use it.

However, it may be risky, therefore I feel it is best to go with a standard one.

You might be wounded while using an electric saw, particularly if you attempt to grip the top piece of the mattress to keep it from slipping off while you’re cutting.

In this scenario, a normal saw is much safer.

A hot wire is another alternative (if you manage to find a wide enough model for your mattress).

Keep in mind that this procedure requires a very steady hand.

Also, if you lay the mattress on a higher platform, it may be easier for you to cut it.

Having said that, I do not propose cutting your mattress horizontally.

It’s the simplest way to ruin the foam.

Furthermore, there is no assurance that your “new” mattress will be comfortable enough.

Instead, you should think about obtaining a new one.

I’m certain you’ll discover an appropriate thickness selection among the finest memory foam mattresses recommended by Reddit users, for example.


Is It Permissible To Cut Memory Foam?

Yes, as long as you are patient with it, it should be OK.

To avoid harming the texture of the material, avoid compressing it or applying too much power while using the knife.

Is It Possible To Cut Memory Foam With A Hot Knife?

In theory, you can, but using a hot knife might harm the foam and cause it to lose its form.

A standard knife is sufficient if it is sharp enough, thus there is no need to use a hot knife.

Is It Possible To Cut A Gel Memory Foam Mattress?


Because the gel particles are integrated with foam, there is no risk of gel escaping if you chose to cut your mattress.

How Do I Use a Hot Wire to Cut Memory Foam?

The easiest approach to cutting memory foam with a hot wire is to take the memory foam outdoors, turn on your hot wire cutter, and make cuts where you need them on the memory foam.

Memory foam cuts readily with a hot wire, but since the wire melts some of the foam, hot wire cutting should always be done in a well-ventilated environment to minimize fume exposure.

How Do I Dispose of a Memory Foam Mattress?

The following is the easiest approach to cutting up a memory foam mattress for disposal:

– Take the mattress outdoors or place it on a plastic sheet.
– Using a knife, cut away the pipe.
– Remove the cover and side panels using a knife, being careful not to cut any staples.
– Cut the memory foam and foam core layers separately using a knife, bigger scissors, or a tiny saw.
– Place the little fragments of memory foam in plastic bags to be disposed of.


Who says you can’t construct your own custom-size memory foam mattress?

All you need is a good knife and a ruler.

And, certainly, sometimes.

However, as a consequence, you may acquire almost any mattress measurements you choose.

Just be sure to treat the foam gently and not crush it too much throughout the procedure.

After all, your “new” mattress will need to preserve its qualities, right?

Why should you trim your memory foam mattress?

Are you attempting to acquire a certain size or shape?

Tell us in the comments section below!

Suggestion Videos from Youtube About Cut Foam Mattress

Cutting a Foam Mattress in Half – Lefie
How to Cut a Foam Mattress | Vanlife Bed – TheGalavan
How to cut memory foam – Tobicat University


(1) Washington State Department of Health (n.d.). Fiberglass. Retrieved from 

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Ryan is a RV product expert with nearly a decade of experience researching, developing, and testing RV products.

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