Everything this stopwatch does
Precision and units
- Six precisions: whole seconds, 1/10, 1/100, 1/1,000, 1/10,000 and 1/100,000 of a second (10 microseconds). Switch with the buttons or the keys 1–6 at any time — the time underneath is kept at full resolution, so nothing is lost.
- Eight units: clock time, decimal seconds, milliseconds, microseconds, decimal minutes, decimal hours, TMU (the units of industrial time study), and SMPTE video timecode at 23.976, 24, 25, 29.97 (drop-frame or non-drop), 30, 50, 59.94 and 60 fps.
- Timed from the press. The start, stop and lap times come from the input event itself — the moment the key or button went down — not from whenever the page got round to handling it.
- Timing details: open the panel to see your browser's measured clock tick, your screen's refresh rate, the exact start time and the raw elapsed time in milliseconds to three decimals.
Laps, pace and targets
- Every lap shows its time, the running split, the difference from your average (or your target) and from the previous lap, and the time of day it was taken — and you can type a note against it.
- Distance per lap adds pace (per km or per mile) and speed for every lap — set 400 m for a track, 25 or 50 m for a pool.
- Target lap time shows ahead or behind live on the current lap. Planned laps projects your finish from the laps so far.
- Statistics: average, median, fastest, slowest, spread, consistency, and the trend — whether you're getting faster or slower per lap — plus a lap chart with your average and target drawn in.
- Undo lap takes back an accidental press; hold the lap time on screen freezes the display for two seconds after each lap so you can read it.
Like a hardware stopwatch
- Freeze display (H) holds the reading while the watch keeps running — the split function of a hardware stopwatch.
- Press twice to stop or reset stops an accidental tap from ending a timing.
- Countdown to start from 3 to 30 seconds with beeps; an alarm at any time, once or repeating; beeps and spoken lap times.
- Full screen, a small always-on-top window (Chrome and Edge), and the screen kept awake while it runs.
Your data
- It survives a reload: closing the tab, refreshing or restarting the browser doesn't lose a running stopwatch.
- Every reset is kept in Past sessions on your device, ready to reopen.
- Export laps as CSV or JSON, copy them as text, or copy a ready-made Markdown table.
Keyboard shortcuts
| Key | Action |
|---|---|
| Space or S | Start / stop |
| L or Enter | Lap |
| U or Backspace | Undo the last lap |
| H | Freeze / release the display |
| R | Reset (when stopped) |
| F | Full screen |
| M | Sound on / off |
| 1 – 6 | Precision: 1 s, 1/10, 1/100, 1/1,000, 1/10,000, 1/100,000 |
Which precision should you use?
| Precision | One step | Good for |
|---|---|---|
| 1 s | 1 second | Cooking, study, meetings — anything long. |
| 1/10 | 100 ms | Hand timing of races: it matches how consistent a human start and stop really is. |
| 1/100 | 10 ms | Laps, training, most sport and lab work — what most hardware stopwatches show. |
| 1/1,000 | 1 ms | Comparing very close results; keystroke-to-keystroke timing. |
| 1/10,000 | 100 µs | Seeing the clock itself; comparing input devices. |
| 1/100,000 | 10 µs | The finest digit a browser's timer can resolve — best in Chrome and Edge. |
The clock is far finer than your finger. Human reaction time is around a fifth to a quarter of a second and varies by a few hundredths from press to press, so for hand timing the tenths are the honest digit. The finer digits are exact readings of the clock at the moment of each press — useful for comparing devices, curious about timing, or when the start and stop come from the same rhythm.
This site asks the browser for its fine-grained timer, which Chrome and Edge resolve to about 5 microseconds. Some browsers deliberately coarsen it; the precision note under the buttons, and the Timing details panel, tell you what yours does. The display is always truncated, never rounded up — 9.99999 shows as 9.99 at hundredths, the way hardware stopwatches behave. More in how accurate is an online stopwatch?
26 faces — and you can put any of them on your own site
The big digits are only one way to read time. Open Face above the display to switch this stopwatch to a flip clock, nixie tubes, a chronograph with a sweeping hand, a radar sweep, an hourglass, a word clock and more. Every face works as a clock, a stopwatch and a countdown, and the choice is remembered. Browse them all in the clock face gallery, or see the time right now on the online clock and the world clock.
Everything on Stopwatch.ca can be embedded for free: pick a face, a colour and a size in the generator, copy one line of code, and paste it into your page. It suits classrooms, gyms, streams, shop windows and event pages.
Other ways to time
Timing several people at once? Use the multi-stopwatch and its race mode. Running segments against a personal best? The split timer. Studying a job element by element? The time study stopwatch. Need to count down instead? The countdown timer or interval timer.
Questions
How do I use the stopwatch?
Press Start, the space bar, or tap the big display. Press Lap (or L) to record a lap while it runs, Stop to pause, and Reset to clear it once it's stopped. Resume continues from where you stopped, and U undoes a lap.
Can a stopwatch measure 1/100,000 of a second?
This one can display it: choose 1/100,000 for steps of 10 microseconds. In Chrome and Edge the browser's timer resolves to about 5 microseconds, so the digit is a real reading of the clock at your press. Your reaction time varies far more than that, so for hand timing, read the tenths or hundredths.
Can the stopwatch show milliseconds or microseconds?
Yes. Choose 1/1,000 for milliseconds in the clock display, or switch the units to Milliseconds or Microseconds to show the whole elapsed time in ms or µs.
Does the stopwatch keep running if I close the tab?
Yes. The start time is saved on your device, so if you reload, close the tab or restart the browser, the stopwatch shows the correct elapsed time when you return. Clearing your browser's site data resets it.
Can it show my pace per lap?
Yes. Enter a distance per lap — 400 m for a track, for example — and every lap shows its pace per kilometre or mile and its speed, with average pace and total distance in the statistics.
Can it show video timecode?
Yes. Set the units to Timecode and choose a frame rate from 23.976 to 60 fps, including 29.97 and 59.94 drop-frame, which shows a semicolon before the frames.
Can I make the stopwatch full screen?
Press F or the Full screen button. In Chrome and Edge you can also use Float on top to keep a small stopwatch window above other tabs and apps.