Stopwatch
The Stopwatch measures elapsed time with millisecond precision. Start, stop, and reset the stopwatch, and record lap times to track multiple intervals. This tool is useful for timing races, workouts, cooking, experiments, presentations, and any activity that requires precise time measurement. The stopwatch continues running even when you switch to other applications.
Formula
Stopwatch operation: - Start: begins timing - Stop: pauses timing - Reset: returns to zero - Lap: records split time - Display: HH:MM:SS.mmm Precision: milliseconds (1/1000 second) Accuracy: JavaScript performance.now()
Example
Start: 00:00:00.000 After 10 seconds: 00:00:10.234 Lap 1: 00:00:15.567 Lap 2: 00:00:30.123 Stop: 00:00:45.890 Total time: 45.890 seconds
How to Use
- Click start to begin timing
- Click lap to record split times
- Click stop to pause timing
- Click reset to return to zero
- Review lap times in the list
Frequently Asked Questions
How accurate is the stopwatch?
The stopwatch uses JavaScript's performance.now(), which provides millisecond precision. For most uses, accuracy is within a few milliseconds. For professional sports timing, use dedicated timing equipment certified for the sport.
Does the stopwatch work when I switch tabs?
Yes. The stopwatch continues running in the background tab. When you return, it shows the correct elapsed time. However, some mobile browsers may throttle background tabs, which could affect lap timing accuracy.
How many lap times can I record?
There is no practical limit. You can record as many laps as needed. Each lap shows the split time (time since the last lap) and the total time. Laps are displayed in a list for easy review.
Can I export lap times?
The stopwatch displays lap times in a list. You can copy the list manually. For automatic export, some stopwatch tools offer CSV or text export. Check the tool's features for export options.
What is the difference between a stopwatch and a timer?
A stopwatch counts up from zero (measuring elapsed time). A timer counts down from a set time to zero (counting remaining time). Use a stopwatch to measure how long something takes. Use a timer to count down to a deadline.