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Is it ok to Cut a Memory Foam Mattress? And How to cut it


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When it comes to mattresses, memory foam provides a stiffer, more enjoyable surface to sleep on than most bedding materials.

It conforms to your body shape, allowing you to sleep more comfortably, and there are claims that it helps with back pain.

Given how wonderful memory foam is, you may want to try it out for yourself; however, finding memory foam mattresses pre-cut to fit your needs might be harder than you think.

So, is it okay to cut a memory foam mattress? Yes, you can cut a memory foam mattress to your requirements. All you need is a cutting tool, a tape measure, and a marking pen. However, some mattresses contain extra materials such as gel and fiberglass which makes them harder to cut.

Read on to learn about why you would want to cut your memory foam mattress and how to do so.

If you are interested in checking out the best rated memory foam mattresses currently available on the market, you can do so on Amazon here.

Why Would You Want to Cut Your Memory Foam Mattress?

You may want to cut up your memory foam mattress for various reasons, such as:

  • Fitting it onto a smaller bed
  • Fitting it to an unusual area such as inside a boat or a van
  • To turn a bigger-sized mattress into two singles
  • To customize your mattress for an unusual bed frame
  • To reuse the mattress for other applications such as making makeshift pillows, seat cushions, mats, padding for a headboard, and more.

Whatever your reason, when cutting memory foam, getting a straight, clean cut is crucial; however, this will most definitely void your warranty.  

How to Cut a Memory Foam Mattress

1. Collect your tools

The biggest problem you might face when cutting memory foam is getting a clean edge. Using the wrong tool or a blunt one will make the edges jagged and rough, which might cause it to break down.

Even using the right tool too aggressively will result in jagged, rough edges. Before you can cut up your memory foam, you want to pick the right cutting tool. Here are a few choices to choose from:

1. Carving knives

These knives have serrated blades, unlike the smooth edges found on regular knives. The serrated tips are key to getting a clean edge, so use short, gentle back and forth motions to cut through the memory foam and avoid applying too much pressure and compressing it.

2. Electric knives

Similar to carving knives, these also have a serrated blade. They are ideal for cutting the foam into odd shapes or when using a template. Just place the blade along the edge and cut along your template.

3. Utility knives

These can also be used to cut memory foam since they are surgically sharp. However, unlike serrated knives, they have a smooth edge, so instead of sawing through the foam as you would with a serrated knife, you have to make light passes to cut the foam.

Start by cutting an initial shallow outline, then repeat the process to deepen the cut until you cut through the foam.

4. Heavy-duty scissors

These are a great safe way to cut through thinner pieces of memory foam such as a mattress topper that’s less than ¾ inches thick. Use short chops as you cut, and be wary of snipping your fingers.

Work with caution

Always use caution when cutting foam with any cutting tool and wear protective gear such as gloves, breathing, and eye protection.

If you make a mistake or you are cutting odd shapes and forms, you can glue the foam back together, just use spray adhesive made for memory foam. Spray it on both pieces and stick them together. Be very careful because they bond on contact, and if done right, you might not see the splice lines.

You will also require a ruler, tape measure, or a drywall square to help you measure and cut your foam. Alternatively, you could use a piece of plywood, hardboard, or anything with a long straight edge to measure and cut the foam with.

You will also need a marking pen to draw an outline or template or just freehand it. 

After collecting your tools, make sure you remove the slipcover that comes with most memory foam mattresses. The slipcover offers an added layer of protection for the mattress. Look for a zip around the edges; if there’s none, you may need to cut the cover off. 

2. Check and mark up the dimensions you will need

Before you start cutting the memory foam, you have to determine the size and thickness you need. For instance, if you are fitting your mattress into a boat, it can’t be too tall.

Use the tape measure or ruler to double-check the dimensions you need: that is, the height, width, and depth of the memory foam needed.

After double-checking your measurements, add about ⅛ inches to them, then mark up the mattress; that is, create an outline of where your cut lines will be. The extra ⅛ inch serves as a buffer since cutting the foam removes some of the material.

Ensure you don’t compress your memory foam as you take your measurements, or else they will be inaccurate. Since memory foam flattens easily, it’s best to have a medium-density overlay over a high-density mattress; this way, you prevent it from collapsing completely when flattened, and it’s still comfortable.

Luckily a lot of brands are designing memory foam with this in mind, so be prepared to find different layers of memory foam in your mattress.

3. Make your cuts

When cutting memory foam, you want to get clean straight edges, so set the foam on a flat surface, preferably a table with the side you are cutting hanging over the edge. Make sure the surface is sturdy because you don’t want to compress the cut line as you cut.

Put something heavy on top of the mattress to hold it in place but keep it away from your cut line; this way, you don’t affect the cut. Holding the cutting tool such as an electric carving knife perpendicular to the foam, make a straight cut following the outline you made.

Ensure the serrated blade is following the outline you drew. If you can’t find an electric carving knife, a bread knife will work just as well.

However, do or put pressure on the cut line. If the knife is too short to cut all the way through, follow the utility knife method: make a shallow cut, then repeat the process to deepen the cut until you cut through the foam.

If you are cutting through a thick mattress, you may need to flip the mattress over, so make sure to outline both sides and ensure they are the same.

The bottom of the foam might be harder to cut because it may have a different density than the rest of the memory foam. That said, it’s a lot easier to cut through it than the softer part because the latter tends to warp as you cut.

4. Trim off any excess material

After cutting the shapes you desired, make sure to trim off the excess. You don’t have to stress about the presentation if you are putting a mattress cover over the piece. Decide whether you will buy a new mattress cover or cut and restitch the old one to fit your new mattress.

How to Cut up a Memory Foam Mattress Topper

A memory foam mattress topper is a great way to revitalize an aging mattress or soften a new mattress that is too hard. Whether you’re making your own topper or buying a new one, you may have to trim it, so it fits the actual mattress. Luckily trimming a memory foam mattress topper is quite simple.

Start by deciding what size topper you will need. For instance, if it’s for a twin bed, it will be 39 x 75 inches; a long twin mattress will be 39 x 80 inches.

If you want a topper for the foam you cut up previously, just use the same measurements. Just like you did when making your outline for the memory foam mattress, add the ⅛ in buffer.

Next, lay the topper on a raised flat surface, and make an outline of where you need to cut. With a carving knife or a pair of scissors cut along the outline you made, often stopping to ensure you haven’t gone off course. Trim off the excess and refit the mattress cover.

Consider Using a Foam Cutting Service

Cutting memory foam vertically is pretty straightforward; however, it’s important to note that some foam mattresses might contain extra materials such as gel, which is used to regulate body temp or fiberglass that acts as a fire retardant.

These additional materials might make cutting your memory foam harder. Luckily you can use a foam cutting service to trim your foam into the shape you need.   

If you are interested in checking out the best rated memory foam mattresses currently available on the market, you can do so on Amazon here.

Niklas Lampi

My name is Niklas and I'm the author and content operator at The Bedding Planet. I've always had a big interest in bedding and more specifically sleep. If I find something that makes me sleep better, whether that's a lifestyle change or a better bedding environment, I'm ready to share it with the world!

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