How to Accurately Measure a Pillow Cover
Pillow cover sizes are based on the measurement from seam to seam. A pillow cover may sometimes appear smaller if you are measuring it from the front because the sides may be folded in a bit. For this reason, to get the most accurate measurement, you would turn it inside out, lay it flat, and measure it from seam to seam. The photos below show a pillow that measures 19 inches. Notice how the yardstick is lined up with the seam.
1. Turn pillow cover inside out and lay it on a flat even surface.
2. Line up measuring stick or tape with the seam on one side
3. Line up the measuring stick/tape with the seam on the opposite side. In the photo below, the pillow cover measures 19 inches wide.