Stopwatch
Start, pause and record laps with split times — exact even in background tabs.
Press Start to begin
Keyboard: Space start / pause · L lap · R reset
Laps
| Lap | Lap time | Total (split) |
|---|
Press Lap (or L) while the stopwatch is running to record lap and split times.
About the Stopwatch
A precise stopwatch in your browser. Start it, record laps, and pause or resume as often as you like. It shows hundredths of a second and keeps a table of every lap with its lap time and total (split) time, with the fastest and slowest laps highlighted.
Time is measured from timestamps instead of by counting ticks, so the stopwatch stays exact when you switch tabs, lock your phone or reload the page — it is saved in your browser and carries on where it was.
How to use it
- Press Start (or the
Spacekey) to begin timing. - Press Lap (
L) at the end of each lap. The table shows how long each lap took and the total time when you pressed it. - Press Pause (
Space) to stop the clock and Resume to carry on. Reset (R) clears it while paused — you can undo a reset for 15 seconds. - Use Export CSV or Copy to keep your lap times.
Examples
Lap pressed at 01:32.40, 03:06.10 and 04:37.95
Lap 1 01:32.40 Lap 2 01:33.70 (slowest) Lap 3 01:31.85 (fastest)
Lap,Lap time,Total time,Lap (s),Total (s),Note 1,01:32.40,01:32.40,92.400,92.400, 2,01:33.70,03:06.10,93.700,186.100,Slowest 3,01:31.85,04:37.95,91.850,277.950,Fastest
The seconds columns are exact to the millisecond, ready for averages and charts in a spreadsheet.
Common uses
- Timing laps and intervals in running, swimming or cycling training.
- Timing speeches, presentations, exam answers or practice rounds.
- Measuring how long a task takes for estimates or time studies.
- Classroom experiments and games.
Lap time or split time?
A lap time is how long one lap took: the time between two presses of Lap. A split time (shown as Total) is the total time on the clock at the moment you pressed Lap.
For example, if you press Lap at 01:32.40 and again at 03:06.10, lap 2 took 01:33.70 and its split time is 03:06.10.
Keyboard shortcuts
Space— start, pause and resumeL— record a lap while runningR— reset while paused
When another button such as Undo, Copy or Export CSV has keyboard focus, Space presses that button as usual. Shortcuts are ignored while you type in a text field. If they get in the way (for example with a screen reader), switch them off under the lap table.
How accurate is it?
Every reading is calculated from the moment you pressed Start and your device clock, so the stopwatch cannot fall behind even when the browser slows down background tabs. The display refreshes with your screen and shows hundredths of a second; the CSV export keeps each lap to the millisecond.
In practice, your reaction time when pressing the button is a far bigger source of error than the stopwatch itself.
Limitations
- Hand timing depends on your reaction time; it is not a substitute for electronic timing at competitions.
- If the device clock is changed while the stopwatch is running, the reading jumps by the same amount.
- Up to 999 laps are kept per session.
- The saved stopwatch lives in this browser only; private or incognito windows forget it when they are closed.
Privacy
Everything happens in your browser. What you enter or open here is not uploaded or stored by MySmartCoPilot.
Frequently asked questions
Does the stopwatch keep running if I switch tabs or lock my phone?
Yes. It calculates the elapsed time from the moment you pressed Start, so it is correct as soon as you come back, even hours later. It also survives reloading the page or reopening the browser on the same device.
Can I use it with the keyboard?
Yes: Space starts and pauses, L records a lap and R resets when paused. Every button also works with Tab and Enter.
How do I save my lap times?
Use Export CSV for a spreadsheet file with lap times, totals and exact seconds, or Copy to paste the table into a document or chat.
Why can I only reset when the stopwatch is paused?
So a running time is never lost by accident. Pause first, then reset; if you reset by mistake, press Undo within 15 seconds.
Can I show it on a big screen?
Yes. Press Full screen (where your browser supports it) to fill the screen with the time and the controls.