When sofa cushions go flat you may feel like you're sitting on wooden boards. Essentially, you are sitting on wooden boards when your cushioning is old and/or worn out. Restuffing or refilling your sofa cushions is necessary every few years to keep your couch functioning as a comfortable place to sit or recline. Fixed sofa cushions are cushions that are permanently attached to your sofa, and these can be a bit trickier to fill.
Measure your sofa cushions with the measuring tape. Measure how long and how wide they are. Subtract two from each measurement. So if your cushions measure 18 by 25 inches, your numbers should be 16 by 23 inches.
Measure out the subtracted numbers on the foam pad.
Outline with a sharpie.
Cut the pieces along the drawn edges with the razor blade or another smooth blade.
Use the seam cutter to rip open one side of the seam on your cushion.
Remove the previous stuffing, or push it down and put the foam pad on top of the old stuffing.
Put as many layers as you need to feel comfortable.
Sew up the seam.