How To Cut Foam Using Knives

Cutting foam is an easy task that everyone can manage to do with simple tools such as a utility knife or an electric knife. For bigger piece of foam, you can use a band saw with the same techniques. When you have the right equipment on hand, all you need to do to cut foam is following some basic steps. There are some efforts and patience you need to pay for this project but it would be all worth it in the end.


If you are interested on learning how to cut foam, scroll down to read on!

Before cutting foam, you need to prepare these following items:

  • Foam
  • Utility knife
  • Electric knife
  • A taping measurer or ruler
  • A pen

Here are the basic steps for cutting foam:

Step 1: Using the taping measurer, the ruler and the pen to measure on the foam and mark the lines which you want to cut the foam into.

Step 2: Put the foam on the floor. Or if it is more convenient for you, put it on a working table with clean and level surface. To prevent yourself from marking the working surface while you cut the foam, place an extra piece of plywood under the foam.

Step 3: Turn on the electric knife or hold the utility knife and move it along the line that you have drawn on the foam. Make sure that you move the knife slowly in order to follow the drawn line easily. Keep in mind that you need to cut thin lines only. Don’t press too hard on the foam.

Step 4: Use the tip of the blade to cut into the foam with the depth of around 0.25 inches. If you have to cut a straight line, you can use a straight ruler and place it along the line you want to cut your foam into. Then slowly move the knife along the ruler.

Step 5: Continue to cut into another 0.25 inches of the foam or deeper using the tip of the blade.

Step 6: When you finally manage to cut though half of the width of the foam board, push on the knife harder so that it would cut through the final depth of the foam.

Step 7: When the blade successfully cut through the foam board, run the knife along the drawn lines iin one stroke to cut the board clearly.

Step 8: Move on to other section of the board and repeat step 4 to step 8.

Extra helpful tips:

1. How To Choose Foam

Foam is available in most of the craft stores. There are different types of foam with different thickness and sizes. Choose the type you prefer for your specific purpose. Soft foam would be needed for decoration while thicker foam can be used for cushioning. If you need to cut foam for your cushions, measure the dimensions of the cushion cover, especially the thickness, to make sure you buy one that fits.

Also keep in mind that since you are going to cut foam with knife by yourself, you should go for a piece of foam which is not too dense. Dense and rigid foam would be way much harder to cut. You can touch the foam with your finger to check how rubbery it.

Most of the foam products on the market come with colored codes. The black code represents the thickest pieces of foam. The light blue coded foam is less thick than the black one and the green coded foam is the thinnest piece of foam.

2. Which Knife To Use?

I have mention about 2 types of knives which you can use to cut foam including utility knife and kitchen knife. You can use both of these knives for cutting the same foam board of the same thickness. However, if you are going to cut a thicker piece of foam board, or in case you have to cut a huge amount of foam, you should go for the electric knife. This tool also provides a nice and smooth cut for you.

In other hand, if you want to cut foam with small and finer details, using a utility knife is the better option. You would be able to control your speed of foam cutting better.

Last but not least, if you have to cut large thick piece of foam, or in case you have to cut multiple pieces, go for a band saw. It is more difficult to set up and use. However, it would be really efficient for the task. Here are the simple steps on cutting foam with band saw.

  • Prepare the ¼ inches saw blade on your band saw.
  • Put the foam into the band saw table and mark the lines that you want to cut.
  • Turn on the band saw and slowly move the foam towards to blade following the lines you have drawn.
  • Finally, saw the cut edges with 100 grit sandpaper to smoothen the edge of it

3. Safety Caution

While cutting foam is an easy task even for a clumsy person, there are some things that you need to know in order to prevent yourself from getting hurt while working on this project:

  • Never move the knife towards yourself or any part of your body.
  • No matter what you are going to use, remember to sharpen the blade of the knives. Sharp blade is capable of cutting nice and clean cut. Not to mention that sharp blade reduce your risk of getting injuries.
  • Dust can be form from the cutting process. So always wear the safety goggles and a dust mask to prevent dust from getting into your eyes and your respiratory system.


As you can see, there are several methods which you can use to cut foam. Still, the most popular method for you to cut foam board at home is with a utility knife or kitchen knife.

I hope that this article below would be able to provide you much information about how to cut foam in the most efficient way. Keep in mind these guides and extra helpful tips and I am sure that you would master this technique in a short amount of time.

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