A stopwatch is a timepiece designed to measure the amount of time elapsed from a particular time when activated and when the piece is deactivated.

The watch is typically designed to start measuring time at the push of a button and stop by pressing the button a second time to stop measuring time elapsed.

The device is used in events when time periods must be measured exactly and with a minimum of complications. Sporting events like sprints are a major example.

The stopwatch function is also present as an alternative function of many digital wristwatches. If an analog wristwatch has a stopwatch function, it is called a chronograph.