When it comes to cutting a mattress, the task may seem daunting at first. However, with careful planning, the right tools, and a bit of patience, it’s a job that can be accomplished. The key to cutting a mattress is using a sharp utility knife or an electric carving knife, measuring and marking your cutting line precisely, and cutting with steady, controlled strokes. Remember to keep safety in mind at all times to prevent accidents.
Preparation for Cutting a Mattress
Before you start the physical process of cutting, you should carefully plan and prepare. Clear out a large workspace, preferably on a flat, solid floor surface, and make sure that you have ample room to maneuver around the mattress.
Gather Necessary Tools
You will need the following items:
- Measuring tape: To measure and mark the cut accurately.
- Permanent marker: For marking the cutting line on the mattress cover.
- Utility knife or electric carving knife: A sharp utility knife can be used for most mattresses, while an electric carving knife can make the job easier, especially for memory foam or thicker mattresses.
- Straight edge or yardstick: This will help you draw a straight cutting line.
- Scissors: Needed to cut through the mattress cover and any fabric layers.
- Gloves and Safety goggles: Essential for protecting your hands and eyes during the cutting process.
Plan Your Cut
Measure your mattress and decide where you want to make your cuts. It’s essential to be precise in this step to avoid a jagged or uneven cut. Use your marker to draw a guideline where you will make the incision. If you’re cutting to resize your mattress, double-check your measurements to ensure they will fit the desired space.
Our Top 5 Mattress Picks
Updated September 2026EGOHOME 8-Inch Green Tea Memory Foam Mattress, Full, Medium Firm
Best for most bedrooms. A medium-firm green tea memory foam mattress with a cooling gel layer, delivered rolled in a box.
- Full size, 8 in
- Medium firm
- Cooling green tea gel
- CertiPUR-US, fiberglass free
OhGeni Queen Air Mattress with Built-in Pump, 18-Inch Raised
Best for guests and camping. Inflates in about three minutes with the built-in pump and sits 18 inches off the floor, so it feels like a real bed.
- Queen, 18 in raised
- Built-in pump
- 800 lb capacity
- Waterproof PVC
Novilla 6-Inch Gel Memory Foam Mattress, Twin
Best budget twin. A slim gel memory foam twin that suits kids' rooms, bunk beds and trundles where a thick mattress won't fit.
- Twin, 6 in
- Gel memory foam
- Cooling
- CertiPUR-US
Zinus 8-Inch Green Tea Memory Foam Mattress, Twin
Best-known brand. Zinus's long-running green tea foam design in twin size, with both CertiPUR-US and OEKO-TEX certified materials.
- Twin, 8 in
- Green tea memory foam
- CertiPUR-US & OEKO-TEX
GAESTE 8-Inch Cooling Gel Memory Foam Mattress, Full, Medium Feel
Best for hot sleepers. Cooling gel memory foam with a medium feel, plus a machine-washable, anti-slip cover you can actually clean.
- Full size, 8 in
- Medium feel
- Cooling gel foam
- Washable cover
- Fiberglass free
Steps to Cut a Foam Mattress
Foam mattresses are among the easier types to cut due to their material consistency. Here’s a step-by-step guide:
Step 1: Remove the Cover
If the mattress has a removable cover, take it off. If not, use scissors to carefully cut and remove the cover along the marked line.
Step 2: Mark Your Line
Lay the mattress flat on the ground. Make sure there are no wrinkles or folds. With the straight edge and the marker, draw a clear and straight line where you wish to cut.
Step 3: Begin the Cut
Place the straight edge along the marked line. With the utility knife or electric carving knife, start cutting along the edge. Work slowly and do not rush this process. If using an electric knife, let the blade do the work without applying excessive pressure.
Step 4: Continue Cutting With Care
Continue your cut, always ensuring the knife is at a 90-degree angle to the mattress for a straight edge. You may need to go over the same section several times.
Step 5: Finish the Cut
Go over any rough edges to smooth them out.
Steps to Cut an Innerspring Mattress
Innerspring or coil mattresses require more effort due to the metal springs inside.
Step 1: Remove the Cover
Like with the foam mattress, begin by carefully removing the mattress cover.
Step 2: Peel Back Layers
Innerspring mattresses have layers of padding on top of the springs. Carefully peel back these layers to expose the spring unit.
Step 3: Cut Through the Springs
Depending on the gauge of the wire, you might need bolt cutters to cut through the springs. Take your time and work with care to avoid leaving sharp edges.
Step 4: Trim Excess Material
Once the springs are cut, trim any excess material and tidy up your work.
Step 5: Reassemble Mattress Layers
After cutting, you will need to reassemble the outer layers and create a new side border for your mattress. This step may require sewing and additional materials.
Finishing Thoughts
Cutting a mattress is not a typical DIY project and should be undertaken only when necessary, as it’s permanent and can affect the comfort and support of the mattress. Always prioritize safety, wear protective gear, and if in doubt, seek professional help. Keep in mind that altering your mattress will void any warranties and could contravene fire safety standards. When the job is done, you will have a custom-sized mattress that fits your specific needs, providing the cut was made cleanly and accurately.
