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Stopwatch
Space start / stop · L lap · R reset · F full screen
Count up instead of down: time a race, a science experiment, a speech, or how long your class really takes to line up.
Stopwatch ideas for the classroom
- Beat the clock. Time a routine such as lining up, write the record on the board, and challenge the class to beat it.
- Science labs. Record reaction times, pendulum swings, or how long an ice cube takes to melt.
- PE and field day. Use laps to record each runner's split.
- Speeches. Show students how long their presentation actually runs.
Need to count down instead? Use a 5 minute timer, theclassroom timer, or pick from all timers.
Stopwatch FAQ
How do I use the stopwatch?
Press Start or the space bar to begin counting up. Press it again to stop. "Lap" records a split time without stopping the clock, and "Reset" returns to zero.
How do you read a stopwatch?
Read it from left to right as minutes, seconds, and hundredths of a second. For example, 01:23.45 means 1 minute and 23.45 seconds. If an hour passes, the hours appear at the front, as in 1:02:03.45.
What is the difference between a stopwatch and a timer?
A stopwatch counts up from zero to measure how long something takes. A timer counts down from a set length and sounds an alarm at zero. See all countdown timers
How accurate is it?
The stopwatch reads your device's high-resolution clock and displays hundredths of a second. It stays accurate even if the tab is in the background.
What does the Lap button do?
It saves the current time without stopping the clock. Each lap shows the time since the previous lap and the total time, which is how you record split times for runners or steps in an experiment.
Can I make the stopwatch full screen?
Yes. Press F or the Full screen button to fill the display — useful for races, PE class, and science experiments.
Last reviewed by the TeachTimer team · How we build and check our tools