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An easy step-by-step guide to cutting memory foam
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Memory foam is a common material used for mattresses and pillows since it is relatively comfortable and it conforms to your body. If you have a piece of memory foam thatโ€™s too large, you can easily cut it at home with an electric carving knife. Be sure to double check your measurements before you make your cut so you donโ€™t make a mistake. When youโ€™re finished, youโ€™ll have a piece of memory foam thatโ€™s the perfect size!

How to Cut Memory Foam: a Quick Guide

  • Add add 1โ„8 in (0.32 cm) to the dimensions you need and then measure and mark the memory foam to the correct size with a marker.
  • Set the foam on the edge of a table so the marked section hangs over the edge and anchor the rest of the foam with a heavy object.
  • Cut the foam along the lines with an electric carving knife. Make sure to hold the knife at a 90-degree angle for a clean cut.
Part 1
Part 1 of 2:

Measuring and Marking the Foam

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  1. Many new memory foam mattresses have a slipcover on top for an additional layer of protection. Look for a zipper around the edge of the mattress and unzip it as far as you can. Once the zipper is undone, pull the edges of the slipcover off of the mattress and remove it. Since youโ€™re cutting mattress, you can either throw away the slipcover or use the material to make a new slipcover. [1]
    • If there isnโ€™t a zipper around the edge of the slipcover, then you may need to cut it off with a knife or pair of scissors.
  2. Use a tape measure to double check the height, width, and depth for the foam you need for your project. For example, you may measure a mattress if youโ€™re cutting a memory foam topper, or you may find the dimensions of a pillowcase if youโ€™re making a pillow. Add 1 โ„ 8 inch (0.32 cm) to each measurement you take since cutting the foam could remove some of the material. [2]
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  3. Hold the end of your tape measure at the edge of your piece of memory foam and pull it out until you reach the correct length. Draw a dot on the memory foam with a permanent marker at the end of your measurement. Move your tape measure along the edge of the mattress by 10 inches (25 cm) and make another dot so itโ€™s in line with the first one. Continue marking the memory foam until you reach the other side. Repeat the process for any other dimensions you plan on cutting. [3]
    • Double check your measurements to make sure theyโ€™re accurate, or else you may make a crooked cut.

    Warning: Be careful not to compress the memory foam while youโ€™re taking your measurements, or else they may not be accurate.

  4. Set a straightedge on top of the memory foam so it crosses the marks you made for your measurements. Use a permanent marker to draw your lines between the measurements so you know where to make your cuts. Make the lines thin so your cuts and measurements are precise. [4]
    • If youโ€™re drawing a curved line, use a round object as a stencil, such as a coffee can or a bowl.
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Part 2
Part 2 of 2:

Making Your Cuts

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  1. Find a flat, sturdy table to set your memory foam on. Position the memory foam on the table so your cut lines overhang the edge of the table. That way, you wonโ€™t damage the tabletop when you cut through the foam. [5]
    • Set a heavy object on a piece of memory foam to help hold it in place if it tips over the edge. Make sure the object is at least 4โ€“5 inches (10โ€“13 cm) from your cut line so the foam doesnโ€™t compress.
  2. Plug in your electric carving knife and hold it with your dominant hand. Position the knife so the blade is at a 90-degree angle to the edge youโ€™re cutting to make a smooth, straight cut. Make sure the serrated edge is touching the memory foam and lines up with the line you drew.
    • You can buy an electric carving knife from any kitchen supply store or online.
    • An electric knife will give you the smoothest cut, but you can also use a serrated bread knife if you donโ€™t have an electric one.
  3. Turn on your electric carving knife and slowly follow along the marker line. Keep your knife perpendicular to the foam so your cut isnโ€™t crooked. Avoid pushing down on the foam while youโ€™re cutting since it could deform and make your cut inaccurate. Continue pushing the blade through the foam along the line until you cut through its entire length. When you need to pull the knife blade out of the foam, turn it off before removing it. [6]
    • Keep your fingers and the knife cord away from the blade while itโ€™s running so you donโ€™t hurt yourself.
    • If youโ€™re using a serrated bread knife, saw back and forth to make your cuts.

    Tip: Lay a straightedge along the line to use as a guide while youโ€™re cutting if you need help keeping the knife straight.

  4. If youโ€™re cutting through a thick piece of memory foam, your knife blade may not cut through it completely. Put the carving knife blade at the end of the cut again and follow along the line again. Work slowly so your cut stays straight and accurate. Continue doing multiple passes over the cut until the blade goes completely through the foam. Repeat the process for any other dimensions you need to cut from the memory foam.
    • You can also flip the piece of foam over to the other side and take your measurements again. Cut through the memory foam so your 2 cuts meet in the middle.
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      Tips

      • You can use a razor knife or serrated bread knife if you want, but it wonโ€™t make as clean of a cut. [7]
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      Warnings

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      Things Youโ€™ll Need

      • Tape measure
      • Marker
      • Straightedge
      • Table
      • Electric carving knife

      About This Article

      Thanks to all authors for creating a page that has been read 138,213 times.

      Reader Success Stories

      • Tania Oro-Hahn

        Mar 28, 2021

        "It worked great! I used an electric knife to make the entire pillow a bit thinner. I started with a clean cut along ..." more
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