The ideal pillowcase hugs its pillow like a form-fitting sock. The perfect fit lends an orderly appearance to both the bed and the bedroom. The average twin-size pillow measures 26 inches long. Using a twin-size pillow with a king-size pillowcase results in an empty sleeve of fabric dangling from the end of the pillow. Hiding the excess fabric, for a clean look, requires a custom fold.
Stuff the twin pillow inside the king-size pillowcase. Slide the pillow all the way down until it reaches the closed end.
Set the pillow flat on the bed. Grab the top of the pillowcase just above the seam.
Tuck the top of the pillowcase in on itself, like folding a letter into an envelope.
Fold the bottom seam into the top seam, creating a snug fit around the end of the pillow.
Grab the tucked in edges of the pillowcase and pull them away from one another, creating a crisp seam across the top of the pillow.
Run both hands across the seam to smooth out any wrinkles.