When you are considering pillows for your sofas, chairs or beds, keep this sizing explanation in mind. Many people make the mistake of holding a tape measure across the center of a stuffed pillow and then assume that this dimension is the correct measurement of the pillow. If they order pillows based on this measurement, the chances are they will be surprised to find that the pillows they receive are actually much smaller than they wanted. The most common sizes of pillows for sofas are 18"x18" and 20"20". However, larger sofas and sectionals, especially those with deep seats or high backs, may be better off with 22"x22" or even 24"x24" pillows.