How to use the Online Stopwatch
- Press Start or hit the spacebar to start timing.
- Press Lap (or the L key) at the end of each section. The table records that lap's time and the total time since you started.
- Press Stop to pause. Press Resume to keep timing from where you left off.
- When you're done, use Copy results to paste your lap times into a text editor, Excel or Google Sheets. Press Reset (or the R key) to clear everything.
Lap time vs. split time
A lap time is how long one section took. A split time is the total time from the start up to that point. If you run three laps of a 400 m track and press Lap after each one, the table might look like this:
| Lap | Lap time | Total (split) |
|---|---|---|
| 1 | 01:52.30 | 01:52.30 |
| 2 | 01:58.10 | 03:50.40 |
| 3 | 01:49.75 | 05:40.15 |
When you have two or more laps, the fastest lap turns green and the slowest turns red, so changes in your pace are easy to spot.
Ways to use an online stopwatch
- Exercise: time each lap of a run, or time planks and interval sets
- Presentation practice: press Lap at each slide to see which parts run long
- Work and lab tasks: time each step of a process or record reaction times in an experiment
- Cooking and games: time each cooking step or how long players take to answer quiz questions
To count down from a set time, use the online timer. To alternate 25 minutes of focus with short breaks, try the Pomodoro timer.
How accurate is this stopwatch?
This stopwatch uses your browser's high-resolution clock (performance.now) and works out the time by subtracting the start time from the current time. The display refreshes dozens of times per second, but the measurement itself doesn't depend on those refreshes. It also stays accurate if you switch to another tab.
Your own reaction time is the bigger factor. People usually press a button 0.1 to 0.3 seconds late, so official race results and other precise measurements need dedicated timing equipment.
Stopwatch or timer: which one should you use?
| Stopwatch | Timer | |
|---|---|---|
| Direction | Counts up from zero | Counts down from a set time to zero |
| Best for | Recording times, checking how long something took, comparing sections | Sticking to a time limit for cooking, breaks or presentations |
| When it ends | When you stop it | An alarm sounds at zero |
| Examples | Your 1 km or 1-mile run time, how long each practice question takes | 3 minutes for instant noodles, 25 minutes of study, a 1-minute plank |
When you study for an exam, using both together works well. Set an overall time limit with the timer, then use the stopwatch's lap button to record how long each question takes. You'll quickly see which types of questions slow you down.