Spin speeds, measured in revolutions per minute (rpm), tell you how fast the drum spins. The faster a drum spins, the more water can be expelled from your clothes, leaving them drier when the cycle is complete. This cuts down the time that your clothes have to be hung up for, and can reduce the time needed in a tumble drier. Budget machines tend to spin slower. If you want the best performance, look for a machine rated at 1400rpm or 1600rpm.