To use the stopwatch online, select Start and the timer counts up in hours, minutes, seconds and milliseconds. Select Lap to record a split, Pause to stop, and Reset to clear. For a countdown, switch to Countdown Timer, set the time or tap a preset, and select Start. You can also press Space to start and pause.
How to use the online stopwatch
- Start timing. On the Stopwatch tab, select Start or press Space. The display shows 00:00:00.000 and counts up.
- Record laps. Select Lap or press L at each split. Each lap shows its own time and the running total, newest first.
- Pause or reset. While the clock runs, the Start button becomes Pause. Pause freezes the clock and Resume carries on from the same time. Lap works only while the clock is running. Reset (or R) clears the time and all laps.
- Use the countdown timer. Switch to Countdown Timer, enter Hours, Minutes and Seconds or tap a preset like 5 min, then select Start. An alarm plays at zero if Sound On is set.
Stopwatch with laps: how split times work
Each time you press Lap, the stopwatch saves two numbers: the total time so far and the lap time, which is the total minus the previous lap's total.
| Lap | Total | Lap time |
|---|---|---|
| 1 | 00:00:30.010 | 00:00:30.010 |
| 2 | 00:00:54.011 | 00:00:24.001 |
| 3 | 00:01:13.852 | 00:00:19.841 |
The panel above the list picks out the fastest and slowest lap, here 19.841 and 30.010 seconds, so you can spot your best interval at a glance. Select Load sample to see this exact example on screen. Laps aren't saved, so write down or screenshot any you need before you reset or close the tab.
Countdown timer with presets
Countdown Timer runs down from any length up to 99:59:59. The preset buttons cover common jobs: 30 sec and 1 min for exercises, 5 and 10 min for breaks, 25 min for a Pomodoro work block, and 1 hour. While it runs you can see the Total set, Elapsed time and Progress as a percentage, and the ring fills as time passes.
Pause stops the countdown and the button changes to Resume, which carries on from where you stopped. Space does the same. Reset, a preset or a new time in the boxes sets it back to the full time. While it runs, the browser tab title shows the time left. At zero the display turns red, the tab title says Time's up and a three-note alarm plays three times, unless you've switched to Sound Off.
Keyboard shortcuts and full screen
| Key | Action |
|---|---|
| Space | Start or pause the active tool |
| L | Record a lap (stopwatch) |
| R | Reset the active tool |
| F | Turn full screen on or off |
Shortcuts are ignored while you're typing in a number box, so click an empty part of the page first. Shortcuts with Ctrl or Cmd are left to your browser.
To show the clock to a class or across a gym, select Full screen or press F. The page hides everything except the running clock, in very large digits, and its Start, Lap and Reset buttons. Press Esc or select Exit full screen to go back. On an iPhone, where Safari can't put a page element into full screen, the clock fills the browser window instead.
Is an online stopwatch accurate?
This one measures time with the browser's high-resolution clock (performance.now()) rather than counting screen updates. If your device is slow or the screen redraws late, the time shown when it catches up is still correct.
Browsers slow down hidden tabs, but that doesn't change the reading: the time is worked out from the clock each time the display updates. The countdown alarm has its own timer that keeps running in a background tab, so it still sounds at zero, give or take about a second. Some browsers keep a page silent until you've clicked or pressed a key on it, which starting the timer does. When you time by hand, your own reaction speed on Start and Stop matters far more than the milliseconds on screen.
For dates rather than seconds, the days between dates calculator counts the gap, and the time zone converter helps you start a timed event at the right moment in another city.
Frequently asked questions
Is there an online stopwatch with laps?
Yes. Start the stopwatch and press Lap or the L key at each split. Every lap shows its lap time and the running total, with the fastest and slowest highlighted.
How do I use the online stopwatch full screen?
Select the Full screen button at the top of the tool, or press F. The clock fills the screen with large digits and its buttons. Press Esc or select Exit full screen to leave.
Does the countdown timer make a sound?
Yes. An alarm plays when it reaches zero, as long as the button at the top says Sound On. It also plays if you've switched to another tab, as long as this page stays open.
Will the stopwatch keep running if I switch tabs?
Yes. It measures real elapsed time, so the reading is correct when you return. The countdown alarm still sounds on time in a background tab, and the tab title shows the time left.
Can I save or export my lap times?
Not at the moment. Laps stay on screen until you reset or close the page, so copy them down or take a screenshot first.
What is the longest countdown I can set?
99 hours, 59 minutes and 59 seconds. The stopwatch has no upper limit and keeps counting past 99 hours.