How to Cut A Memory Foam Mattress? Works For Mattress Toppers Too

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Written by:

Max Stevens
how to cut a memory foam mattress

How to Cut A Memory Foam Mattress? Works For Mattress Toppers Too

You’re here because you want to learn how to cut a memory foam mattress, which means you’ve probably found yourself in one of the situations below:

  • You need to reuse your old memory foam mattress to re-size it for a smaller bed.
  • You need to split a king memory foam mattress intgeo two
  • You need custom-sized memory foam for a seat cushion or any other reason.

Whatever the case is, I’m sure you’re wondering can you cut a memory foam mattress. It can be difficult to slice through cleanly, especially if you don’t know the properties of memory foam and if you don’t have the right tools. Nonetheless, we will share steps to properly cut a memory foam mattress, what tools you’ll need, and takeaway tips to remember.

best tool to cut memory foam & How To Cut Thick Foam?

Memory foam mattress thickness ranges from 20 to 30 cm. This thickness isn’t easy to get through and you risk injuring yourself or damaging the mattress. In addition, these factors can also make it more difficult to cut foam:

  • Mattress firmness
  • Mattress density
  • Number of layers
  • Unique properties of each layer

But with the right tools, cutting memory foam should be pretty easy and straightforward. These tools include:

Electric knife cutting foam

  • Electric knife – This is the best way to cut and the best knife for cutting memory foam as it doesn’t take much effort cutting back and forth. As a result, the cut will be sharp and clean. As long as you keep your hand steady, of course. If you don’t have one readily available, you can use an electric saw with a fine wire to cut the foam.
Kitchen knife used to cut foam

  • Kitchen knife – A sharp kitchen carving knife or bread knife also works for cutting memory foam if you don’t have an electric knife. Short back and forth motions work well with this knife to cut through the foam.

cutter used to cut foam

  • Craft knife – Craft knives are sharp enough to cut through the memory foam. However, these are short blades only, so you have to make shallow slashes and then get gradually deeper resulting in a not-so-even cut as well as taking longer.

scissors used to cut foam

Extra-large scissors -If you don’t have a sharp knife, you can also use heavy-duty scissors. But similar to using a craft knife, it’ll take a lot longer and be more energy intensive.

Other materials you’ll need

  • A ruler or a measuring tape – for measuring the needed dimensions
  • Marker – for drawing lines to aide the cutting process
  • Straight edge cardboard or stick – for outlining

5 Steps To Cut A Memory Foam Mattress


  • Cutting your memory foam mattress will void the product’s warranty. But if you’re past the warranty period, it’s nothing to worry about.
  • Check the label of the mattress if it contains fibreglass. Fibreglass is used on low-cost mattresses as a fire retardant. When cut and exposed to air, fibreglass particles can irritate the eyes, nose, and skin.  In this case, it would not be safe for you to cut the memory foam mattress.

If you’re set on cutting your mattress and know it’s safe to cut, follow the guide below.

Step 1: Take off the mattress cover.

Depending on the manufacturer, your memory foam mattress might have zippers for opening the cover up or no zippers. If there is no opening, use a pair of scissors to cut into the cloth.

You can save the cover for reuse so make sure to cut along the edges for easier restitching later.

Step 2: Measure and mark your cutting area

Once you’ve determined the desired size you want to make a cut line, measure that against your mattress and use a marker to outline where you need to cut. Use a ruler or something a straight-edged piece of cardboard as a guide.

Step 3: Cut the memory foam mattress

Place your mattress on a flat and stable surface and move the marked out line a couple of inches over the edge. When you start cutting, make sure you’re not compressing the foam, as this will change the shape of the edge when cut. An electric knife is your best bet here but there’s plenty of other options we covered above.

Step 4: Trim the rough cuts

Sharp metal scissors

You won’t get a clean cut unless you use a professional machine. So it’s expected to have rough edges which you can trim down to make straight. You can use scissors, electrical knife or rough sanding paper.

Step 5: Cover your new mattress

You can either:
– Reuse your old mattress cover by sewing the fabric using the new dimensions.
– Reuse your old mattress cover by fitting the fabric on the foam and using safety pins to secure the fabric.
– Open up Amazon to buy a new standard-sized mattress cover.
And there you have it, you have your newly piece of foam.

Why Cut Up Memory Foam Mattresses and Toppers?

Through all the years of being in the sleep and mattress industry, we came to the realisation these are the top three reasons for cutting a foam mattress:

  1. Upcycling: Cutting up a memory foam mattress or topper allows you to repurpose the foam for other uses, such as cushioning for seating, padding for pet beds, stuffing for decorative pillows, supportive pillows for sleeping, yoga blocks, padding for costumes, and art projects.
  2. Disposal: Breaking a memory foam mattress or topper down into smaller pieces can make it easier to dispose of, especially if the foam is too large to fit in a standard trash bin.
  3. Cost-effectiveness: Cutting up existing foam is more cost-effective than buying new foam for a specific project.

Bed Sizing Guide

bed sizing guide

illustration of bed sizes with people icon

(Option: illustration of bed sizes similar with BedAdvice)

Can You Safely Cut a Gel Memory Foam Mattress?

Yes, cutting a gel memory foam mattress is possible, as the gel is already infused within the memory foam. There is no risk of leakage, making it safe to modify the size or shape.

To cut a gel memory foam mattress, simply follow the detailed steps outlined above in the article. Remember to take the necessary precautions to ensure a clean, precise cut.

Can A Gel Memory Foam Mattress Topper Be Cut?

gel memory foam mattress

Image: Recci

Now that we’ve covered cutting gel memory foam mattresses, let’s explore the possibility of cutting gel memory foam mattress toppers. The good news is that you can safely cut gel memory foam mattress toppers.

The gel is already infused within the memory foam, similar to gel mattresses, which guarantees that the topper is protected from any damage during the cutting process.

Can you cut memory foam with a hot wire?

Blue Steam Wire
Image: Amazon

Using a hot wire to cut memory foam is an effective method that ensures precision and smooth edges. To cut the mattress into two equal pieces with the original thickness, make a vertical cut. Alternatively, if you want to create a thinner mattress, cut the foam horizontally.

For vertical cuts, follow the previously mentioned methods in the “How to Cut a Foam Mattress?” section. For horizontal cuts, which can be more challenging, consider these expert tips:

  1. Ask a friend or family member to assist you during the process.
  2. Place the mattress on a flat, stable surface to ensure accuracy.
  3. Mark the horizontal line where you plan to make the cut.
  4. Use an electric knife or a hot wire cutter heated to around 350°F to 450°F for optimal results.
  5. Begin cutting along the short side of the mattress, maintaining a consistent speed.
  6. Have your assistant lift the top part of the mattress as you cut through the middle, ensuring a clean cut.
  7. Continue cutting until the mattress is completely separated.

Can A Hot Knife Cut Through Memory Foam?

A hot knife is effective for cutting memory foam due to its ability to melt the foam as it cuts, providing a clean and precise cut. However, it is crucial to distinguish between regular household knives and specialized foam cutting hot knives.

Using a household knife may result in uneven cuts, damaged foam, and potential safety hazards. Instead, opt for a foam cutting hot knife specifically designed for cutting foam materials, UK models include Proxxon 27080 Hot Wire Cutter and the KKmoon Foam Cutter.

  1. Obtain a foam cutting hot knife specifically designed for cutting foam, rather than using a regular household knife.
  2. Be prepared to reheat the knife multiple times during the cutting process, as the blade may cool down.
  3. Heat the knife according to the manufacturer’s instructions, typically by plugging it into an electrical outlet or using a propane torch.
  4. Exercise caution while using the hot knife to avoid accidents and ensure a consistent cut.

Disposing of Your Cut-Up Memory Foam Mattress: A Step-by-Step Guide

Disposing of a cut-up memory foam mattress in the UK may be challenging, but with the right approach, it’s certainly achievable.

First and foremost, consult your local council for specific guidelines on memory foam disposal, as some councils may offer special collection services or designated recycling facilities. Make sure to research the options available in your area to ensure proper disposal. If your council doesn’t provide specific options, contact local recycling or waste management facilities to inquire about accepting the foam.

Another option is donating your cut-up foam mattress to a charity or organisation that repurposes or recycles foam, thus supporting a good cause while contributing to a sustainable future. You could also explore upcycling ideas, such as turning the foam into cushions, pet beds, or even insulation.

Avoid flytipping, as it is illegal in the UK and can result in fines or prosecution. By following your local guidelines, considering recycling facilities, and exploring charitable options, you can responsibly dispose of your cut-up memory foam mattress.

Perfecting the Art of Cutting Memory Foam: Mattresses and Toppers

Did you know? The UK threw away more than 7 million mattresses in 2017, mostly going straight to landfills. So if your memory foam mattress is still in good condition and you’re just looking to make the memory foam firmer, then don’t throw it away. At the very least, use the above repurposing guides.

Besides, with the right tools, steady hands, and patience, you can easily resize your mattress to suit your needs. Ask a friend or partner for assistance for better results since memory foam mattresses are quite heavy.

1 Sources

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

Written by:

Max Stevens