A standard size pillow is 20 inches wide and 26 inches long, and fits a standard-size pillowcase. A standard-size pillow will comfortably fit on a twin-sized bed. Two standard pillows will fit on a full- or queen-sized bed, and three standard pillows will fit across a king-sized bed.

There are three other common types of pillows including queen-size, king-size, and euro-size. The dimensions of a queen-sized pillow are 20 inches wide and 30 inches long. A king-sized pillow is 20 inches wide and 36 inches long, and requires a king-sized pillowcase. The euro-sized pillow is square-shaped and is 26 inches wide and 26 inches long. Decorative pillows, also known as accent pillows, come in a wide variety of shapes and sizes.