An automotive tachometer is used to measure the revolutions per minute (rpm) of both two and four stroke engines, and distributorless ignition systems.

Automotive tachometers use inductive pickup to measure the rpm rate, and the LCD display provides at-a-glance information.

Automotive Tachometers are designed to clip over one of the spark plug wires, then the number of cylinders is input into the machine and it uses this information, coupled with the rate of electrical pulses for calculating the rpm.