How To Cut A Memory Foam Topper To Size

memory topper foam

A good mattress topper is a luxurious thing! But you do not need to buy a ready-made one. If you love DIY stuff, we explain how to make your own.

Creating your own memory foam topper involves taking the correct measurements, purchasing a quality foam, and cutting it according to the dimensions that suit your needs.

Do you have a piece of foam lying around or is your current topper too large? Our guide explains how to create the perfect topper for your mattress. 


How To Cut A Memory Foam Topper To Fit Your Bed

The project is so simple that even beginners can successfully complete this topper. The key is to make sure that you know beforehand how big you want the topper to be. You will then cut the memory foam using those measurements as a guideline. As simple as that, your topper is ready!

However, we need to cover each step in detail because there is more to it than just taking out your measuring tape and cutter. 

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Gather Your Tools And Materials

  • A large surface, like a table or a counter.
  • A tape measure.
  • A slab of memory foam (if you do not already have a topper).
  • Electric carving knife.
  • A ruler.
  • A permanent pen or marker.
  • A helper (you’re going to need an extra pair of hands).

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How To Choose A Slab Of Memory Foam

Some people want to reduce the size of a foam topper they already own. But what if you want to purchase a new slab? Which is the best and what is the best thickness for a memory foam topper?

You will need to talk to a supplier who knows their stuff. This individual or company has to help you figure out what density you prefer (memory foam comes in high-density, medium-density, and low-density). Always shop around and if a slab of foam looks bad, follow your instincts and avoid it. A good slab of foam will look and smell new and bounces back well when you test it.

A final word on choosing a slab – make sure that you get the correct depth. This is a matter of personal preference. You might need a thick slab if your body is sensitive due to arthritis or another condition. Maybe you just want an extra layer of comfort. Whatever your reason, it is essential to find a thickness that feels good to you. This might take some testing but in general, a memory foam topper is between 2.5 cm and 10 cm thick.

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Always buy a larger piece of foam that you need. This way you can customize the perfect size for your bed.

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Determine Your Measurements

taking measurements

Using your measuring tape, take the width and length of your mattress. Once you have those numbers, add a little extra (at most 5 millimetres). This will correct any reduction that might occur when you cut the memory foam. Think of it as a safety margin!

Mark Your Measurements On The Memory Foam

Grab your permanent pen or marker and the ruler. Carefully mark the measurements you took earlier on the memory foam. When you are done, you should be able to see the rectangular outline of your future memory foam topper!

Do not rush the marking process. If you end up with a skewed rectangle, you will have to draw the lines all over again and things will start to look messy. Carefully mark dots from the edge of the foam inwards and connect them to get your width and length. 

Once you are done, do yourself a favour and doublecheck that the rectangle on your foam matches the measurements in your notebook! This last check has saved many people from making a huge mistake. 

Grab all our best tips on how to clean a mattress.

Pro Tip: Always avoid putting pressure on the memory foam when marking. This could affect the accuracy of the measurement transferral. 

Position The Foam For Cutting

For the best results, the memory foam slab needs stability. However, the surface it rests upon must also allow you to cut the foam without any restrictions. This is why most experienced foam cutters suggest that you use a large table or countertop. Both provide stability for the better part of the slab and allow you to freely cut the foam. 

Step 1: Thoroughly clean the table or the countertop. Foam can pick up dirt very quickly!

Step 2: Make sure that your electric carving knife is nearby and remind yourself to use the tool safely. 

Step 3: Choose a side to start with and position it so that the end of this part of the topper is hanging over the edge of the table or countertop.

Step 4: Let your assistant hold the rest of the foam slab firmly in place before you start cutting. He or she must not press so hard or near your cutting area that the foam looks distorted. This will ruin the outcome.

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How To Cut The Memory Foam Topper

Now that everything is ready, you can cut the memory foam. 

Step 1: Take the electric carving knife and make sure that, throughout the whole process, you hold the tip of the knife pointed at the floor. Angling the blade will prevent an even and neat cut.

Step 2: Place the serrated edge against the foam and line it up with the line that will guide your cutting. 

Step 3: Pull the knife along the line and remember, keep that tip pointed at the floor for the smoothest results!

Step 4: Hold onto the foam bar that you are removing until you have cut all the way through the first line.

Step 5: Repeat the process until you have cut along all of the lines.

Add A Slipcover For Extra Protection

beds with slip covers

You can purchase a slipcover or make one. A slipcover will keep the memory foam topper protected and extend its lifetime by many years. 


A Quick Summary On How To Cut A Memory foam Topper To Size

  • Some people need to reduce the size of their memory foam topper.
  • Others want to buy a brand-new memory foam slab and cut it to size.
  • Both can be cut to size using the same technique.
  • Tools include a large surface, electric carving knife, measuring tape, a marker, and a friend. 
  • Using the correct measurements and marked lines, one can cut the perfect memory foam topper to size.  
  • A slipcover can extend the lifetime of your new memory foam topper. 

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About the Author Tom

My journey into the world of sleep came about through living in several properties over my lifetime and always seeming to have the worst luck with neighbors. All but one have been extremely noisy and very inconsiderate. What this made me realize early on, was that the little sleep my neighbors allowed me to get needed to be of great quality. So I started to learn all about sleep, and what helps people get the best quality sleep possible.