Online Stopwatch
Big-digit classroom stopwatch with hundredths, lap times that mark the fastest and slowest lap, and a projector mode.
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A Free Online Stopwatch for Teachers
This online stopwatch counts up in giant digits that the whole class can read, down to the hundredth of a second. Press Lap to record splits: each lap shows its own time and the running total, and once there are three or more laps the fastest is marked in green and the slowest in amber. Teachers use it to time reading fluency checks, races in PE, science experiments and classroom transitions. The time is worked out from the clock, so it stays accurate if you switch tabs. It runs in any browser on Chromebooks, iPads, laptops and interactive whiteboards, with nothing to install and no account.
How to use the stopwatch
Press Start. The stopwatch counts up from 00:00.00. Press Pause to stop it, Resume to keep going from the same time, and Reset to clear it back to zero. Past one hour it switches to hours, minutes and seconds.
Record laps. While it runs, press Lap to save a split. The lap list shows the newest lap first with its lap time and total time, and Copy laps puts the whole list on your clipboard as plain text.
Show it on the big screen. Open Classroom Presentation Mode for extra-large digits with ads hidden. Press Space to start or pause, L to record a lap, R to reset and Esc to exit.
Ways to use the Online Stopwatch in class
Time reading fluency checks
Press Start when a student begins reading a passage and Pause the moment they finish. The digits show the reading time to the hundredth of a second, so you can jot it down and Reset for the next reader. Turn off Show hundredths if whole seconds are all you need.
Run races and laps in PE
Start the stopwatch with the runners and press Lap each time a runner crosses the line or finishes a lap. The lap list shows each lap time and total, marks the fastest and slowest once there are three laps, and Copy laps lets you paste the results into a spreadsheet.
Measure science experiments
Time how long ice takes to melt, a toy car takes to roll down a ramp or a plant cutting takes to wilt in a demo. Press Lap at each checkpoint to log split times, then copy the list as tab-separated text that pastes into a data table as three columns.
Make transitions a challenge
Put the stopwatch in Classroom Presentation Mode and press Space when the class starts lining up or cleaning up. Press Space again when everyone is ready and see if the class can beat yesterday’s time. The giant digits are easy to read from across the room.
Frequently Asked Questions
Is the online stopwatch accurate if I switch tabs?
Yes. The stopwatch measures time from when you pressed Start instead of counting screen updates, so it stays accurate if you switch tabs or your computer is busy. While it runs, the elapsed time also shows in the browser tab title, and on supported devices the screen stays awake.
How are the fastest and slowest laps marked?
Once you have recorded three or more laps, the fastest lap is highlighted in green with a Fastest label and the slowest in amber with a Slowest label. If every lap has exactly the same time, nothing is highlighted.
Can I hide the hundredths of a second?
Yes. Turn off Show hundredths below the controls and the stopwatch, the lap list and copied laps show whole seconds only. Your choice is saved in this browser for next time.
Does the stopwatch keep running if I reload the page?
No. A reload or closing the tab clears the time and the lap list, so copy your laps first if you need them. Only your Show hundredths and sound settings are saved in this browser.
Can I control the stopwatch from across the room?
Yes, in Classroom Presentation Mode. Press Space to start, pause or resume, L to record a lap and R to reset, so a wireless keyboard works from anywhere in the room. The large buttons stay on screen for interactive whiteboards, and Esc exits.
Does the stopwatch make any sound?
It plays a soft click when you press Start, Resume or Lap. Tap the speaker button next to the controls to mute it, and your choice is saved for next time.