Classroom stopwatch
00:00:00.000
This page collects what a classroom actually needs: a large, readable stopwatch for timing activities, lap times to compare repeated rounds of an exercise, a countdown for the minutes you give a group, and a fullscreen mode that takes everything else off the screen.
Classroom uses
Timed exercises
Give a class a fixed number of minutes and show the countdown on the whiteboard.
Repeated rounds
Time each round of a quiz or experiment and compare the lap times afterwards.
Presentations and reading
Keep speakers and readers to their time without counting out loud.
Related tools
- StopwatchStart timing in one click — milliseconds, laps and fullscreen, with nothing to install and no account to create.
- Online stopwatchA free online stopwatch with laps, milliseconds and fullscreen — press Start and time anything in one click.
- TimerPick a preset or type an exact duration and let the timer count down in a display you can read from across the room.
- CountdownSet a target date and time, or just a duration, and watch the remaining days, hours, minutes and seconds tick down.
Classroom questions
What is a stopwatch?
A stopwatch is a tool that measures elapsed time. It counts up from zero in hours, minutes, seconds and milliseconds, and you can pause, resume, reset and record lap splits.
What is a stopwatch used for?
People use a stopwatch for sports training, running splits, workouts, exams, experiments, cooking, games and any task where you need to know exactly how long something took.
How does a stopwatch work?
This online stopwatch measures time from your device clock using timestamps. When you press Start it stores the start moment; the display is computed from the difference, so it stays accurate even if the tab is in the background.
How do I use a stopwatch?
Press Start to begin timing, Pause to freeze the reading, Lap to record a split without stopping, and Reset to return to zero. You can also use the space bar, L, R and F keys.
How do I start a stopwatch?
Press the Start button on this page. The display begins at 00:00:00.000 and counts up immediately — no sign-up, no download, no settings to configure first.
How do I read a stopwatch?
Read the display left to right as hours, minutes, seconds and milliseconds (HH:MM:SS.mmm). Laps below show each split time next to the running total at that moment.
How do I set a stopwatch?
A stopwatch needs no setting — it always starts from zero. Just open this page and press Start. If you need to count down a fixed duration instead, use the online timer.
How accurate is an online stopwatch?
This stopwatch derives elapsed time from high-resolution timestamps rather than an incrementing counter, so it stays accurate during background tabs, screen locking and long sessions. It is suitable for training, study and everyday timing.
Can I use a stopwatch on my phone?
Yes. This stopwatch works on iPhone, Android and tablets directly in the browser. The controls are touch-friendly and the display scales down to small screens.
Can I use an online stopwatch without downloading an app?
Yes — this stopwatch runs entirely in your browser with nothing to install. After your first visit it is cached and keeps working offline too.