Classroom Stopwatch
Make elapsed time easy to see. For experiments, presentations and shared activities.
Lap times
0 completed laps| Lap | Lap time | Split time | Label |
|---|
Make this session yours
No account neededSaved on this device · Pause to save · Up to 20 sessions
Saved sessions 0
A clear view for the whole room.
Measure elapsed time in experiments, presentations or physical education activities. Hundredths are hidden by default for an easy-to-read projector display.
- Name the activity.Add a session name so the class can see what you are measuring.
- Record repeated attempts.Use Lap for segments of one session and enable Show results to review them.
- Keep the scope simple.This first version does not independently time multiple people at once. Use a new session for a separate measurement.
A few useful answers
What is the difference between lap and split?
A lap is the active time since your last mark. A split is the total active time from the start. Marks at 00:12.40 and 00:25.10 give lap times of 00:12.40 and 00:12.70.
Does paused time count?
No. Pause freezes active time. Resume continues the same unfinished lap. Pausing never adds a completed lap.
What is included in a CSV download?
Your session name and recorded laps, with labels, lap times, split times and numeric milliseconds. Unfinished time is not added as a lap. With no recorded laps, CSV contains column headings only; Copy results includes your total time. Formula-like names and labels are prefixed with an apostrophe for spreadsheet safety.
Where are my results saved?
The active session is kept in this tab when browser storage is available. Save session keeps up to 20 paused sessions on this device. Nothing is uploaded by the app. Clearing browser data can remove your results.
Can I use fullscreen or keep the screen awake?
Choose Open Full Screen and leave with Exit Full Screen or Escape. Unsupported browsers use an expanded window view. Keep screen awake is optional and works only when the browser allows it during visible, active timing. It does not promise background or locked-screen operation.
How accurate is the stopwatch?
This is a manual timing tool, not certified competition timing. Hundredths describe the display, not the accuracy of your reaction or device. Background rendering may stop while elapsed time continues. Reloads use the system clock; sleep or clock changes can make recovery uncertain and are flagged. The maximum is 999:59:59.99.
Can I use this stopwatch offline?
After the first successful cache download, the stopwatch and these pages can work offline. Browser storage settings can prevent this. Updates wait until old app tabs have closed.