Stopwatch & Timer
A stopwatch with lap splits and a countdown timer, both running in your browser.
A stopwatch counts up from zero and can record lap splits as you go; a timer counts down from a time you set and alerts you at 00:00. Use the toggle to switch between the two. Both run entirely in your browser — start the stopwatch to time an activity, or set minutes and seconds for the countdown.
Stopwatch and timer, one tool
The toggle at the top switches between two modes. In stopwatch mode the clock counts up from 00:00.00, showing minutes, seconds, and centiseconds; press Lap to mark a split without stopping the count. In timer mode you set a target with the minutes and seconds fields, then count down to zero, where the display flashes and a short tone plays.
The time is computed from real timestamps rather than by adding up ticks, so it stays accurate even if the browser briefly throttles the page. That means the number you read is the true elapsed or remaining time, not a tally that can drift over a long session.
- 1 Pick a mode Use the toggle to choose Stopwatch (counts up) or Timer (counts down).
- 2 Stopwatch: press Start The clock counts up in mm:ss.cs. Press Lap to record a split, Stop to pause, and Start again to resume from where you left off.
- 3 Timer: set the time Type the minutes and seconds you want, then press Start. The display counts down in mm:ss.
- 4 Watch for the alert At 00:00 the timer stops, the display flashes, and a short tone plays if your browser allows sound.
- 5 Reset when done Reset clears the stopwatch and its laps, or returns the timer to the time you set.
Stopwatch vs. timer
The two modes differ in direction, what you set, and what they record.
| Stopwatch | Timer | |
|---|---|---|
| Direction | Counts up from zero | Counts down to zero |
| You set | Nothing — just start | Minutes and seconds |
| Records | Lap splits as you go | Nothing; alerts at the end |
| Ends | When you stop it | Automatically at 00:00 |
| Good for | Timing how long something takes | Limiting an activity to a set length |
Laps, splits, and keeping it running
In the lap list, each row shows two numbers: the split (the time since your previous lap, shown with a +) and the total elapsed time at that point. The split tells you how long that single segment took; the total tells you where you were on the overall clock. Strictly, a “lap” is the time for one segment and a “split” is the running total, but everyday stopwatches show both at once, so this tool does too.
Both modes run in the open browser tab. Keep the tab open and the clock keeps going; the elapsed time is always read from timestamps, so even if you switch away and come back, the number is correct. For structured study, the countdown pairs naturally with the Pomodoro timer, which builds the same idea into fixed 25-minute focus sessions and breaks.