Online Stopwatch
Start, stop and lap a stopwatch accurate to a hundredth of a second, with keyboard shortcuts and CSV export.
Shortcuts: Space starts or stops, L records a lap, R resets.
What this tool does
An online stopwatch measures elapsed time. Press Start (or Space), press Lap (or L) to record a split, and Stop to pause; Reset (or R) clears it. Time is shown in hours, minutes, seconds and hundredths, and laps are listed with the fastest and slowest marked. You can copy the laps or download them as a CSV file.
Runs a stopwatch to 1/100 of a second, measured from the system clock so it stays accurate when the browser is busy.
Records laps with split and total times, marks the fastest and slowest, and exports them.
How to use it
- Press Start, or the Space bar.
- Press Lap, or L, at each split.
- Press Stop to pause and Resume to continue.
- Press Reset, or R, to clear the time and the laps.
- Use Copy laps or Download CSV to keep the results.
Why use this stopwatch
Measures time to a hundredth of a second with start, stop, resume and lap, and marks your fastest and slowest laps. A stopwatch is the simplest way to time a run, a speech, a bake or a workout, and one that runs in the browser needs no app, no install and no account.
Why we built it
We built the online stopwatch with start, stop, resume and laps to a hundredth of a second, keyboard shortcuts and CSV export. Count down instead with the countdown timer and add times with the time calculator.
Related tools worth a look: the Pomodoro Timer and the Instagram Carousel Maker.
Who this tool is for
- Runners, cooks and teachers timing things
- Students timing experiments
- Anyone needing laps to a hundredth of a second
When to use it
- Timing runs, swims, laps and training intervals.
- Timing a presentation, a speech or a meeting item.
- Timing a recipe step, an experiment or a task for a time study.
- Competitive games, speedruns and classroom activities.
How it works
Elapsed time is calculated by subtracting the moment you pressed Start from the current time, rather than adding up ticks of a timer. That means a throttled background tab or a busy page cannot make the stopwatch drift.
A lap records two numbers: the lap time since the previous lap, and the total since the start. Once there are three or more laps, the fastest and slowest laps are marked.
If you switch to another tab the stopwatch keeps measuring correctly, but its display only refreshes when the tab is visible.
What you give it, and what you get back
| Item | Details |
|---|---|
| Controls | Start/Stop (Space), Lap (L) and Reset (R), or the on-screen buttons. |
| Display | Hours, minutes, seconds and hundredths of a second. |
| Laps | A table of lap number, lap time and total time, with fastest and slowest marked. |
| Export | Copy laps as tab-separated text or download them as a CSV file. |
Issues you may run into
| What you see | Why it happens | What to do |
|---|---|---|
| Keyboard shortcuts do nothing | Focus is inside a text box or button. | Click an empty part of the page first, or use the on-screen buttons. |
| Display seems to freeze in another tab | Browsers slow drawing in background tabs. | The elapsed time is still correct; return to the tab to see it update. |
| Laps are lost after closing the tab | The stopwatch does not store data. | Download the CSV before you close the page. |
| Hundredths look uneven | The display refreshes about 30 times a second. | The recorded lap times use the exact clock reading. |
Assumptions and limitations
- Accuracy is limited by the browser clock and your reaction time, not by the display.
- Times are not saved if you close or reload the page.
- It does not sound or vibrate; use the countdown timer for alerts.
Frequently asked questions
How accurate is an online stopwatch?
The clock is accurate to well under a hundredth of a second; your reaction pressing the buttons is the larger error.
How do I record lap times?
Press Lap or the L key while it runs. Each lap shows the lap time and the total, and the fastest and slowest are marked.
What are the keyboard shortcuts?
Space starts and stops, L records a lap and R resets.
Does it keep running in another tab?
Yes. It measures from the system clock, so the time is right when you return, although the display refreshes only while the tab is visible.
Can I save my lap times?
Yes. Press Download CSV for a file you can open in a spreadsheet, or Copy laps to paste them.
Is it free and private?
Yes. It runs in your browser and nothing is sent anywhere.