A single king-size pillow will be sufficient for a queen-sized bed; however, stacking two of these pillows on a queen-sized bed will be troublesome and require more space. They will overlap with one another, leaving little space between them to maneuver. With a king pillow measuring 36 inches in length, you would need a bed 78 inches wide to accommodate two king pillows side by side. On the other hand, a queen pillow is just 60 inches long to accommodate two queen pillows.