Online Stopwatch
Measure elapsed time with start, pause, and reset controls. Your work stays on this device whenever possible.
How to use Online Stopwatch
- Press "Start"; the display counts as MM:SS.cc with hundredths of a second, and the button becomes "Pause" and then "Resume".
- Press "Lap" while the watch is running (it is disabled when paused or reset) to record a lap.
- Read the table with Lap, Lap Time and Split Total; once two laps exist, the quickest is marked green as Fastest and the slowest red as Slowest.
- Press "Export Laps (CSV)" to save stopwatch-laps.csv with the header Lap Number,Lap Time,Split Total.
- Press "Reset" to clear the time and all laps immediately; no confirmation is asked.
Worked example
Press "Start", press "Lap" at about 3.50 seconds, then again at 5.50 seconds. The table shows Lap 1 at 00:03.50 (split 00:03.50) and Lap 2 at 00:02.00 (split 00:05.50), with Lap 2 marked Fastest and Lap 1 Slowest. The CSV rows read 1,00:03.50,00:03.50 and 2,00:02.00,00:05.50.
When to use this tool
- Timing lap splits during a 400 metre training run.
- Measuring how long each step of a recipe or process really takes.
- Exporting lap times to a spreadsheet for a group of runners.
Important limitations
Hidden tabs and sleeping devices can throttle timers. Do not use this for laboratory, billing, sporting, or safety-critical measurement.
Frequently asked questions
How accurate is the timing?
Elapsed time comes from performance.now differences, not counted ticks, so throttling in a background tab does not lose time. The screen refreshes every 25 milliseconds, and human reaction time limits practical precision.
Is there an hours digit?
No. Minutes keep counting past 59, so 75 minutes shows as 75:00.00 rather than 1:15:00.00. Nothing persists across a reload, so the time and all laps are lost when the page refreshes.
What is the difference between Lap Time and Split Total?
Lap Time is the interval since the previous lap. Split Total is the running time since the start, with paused periods excluded because only running time accumulates.
Can I record laps while paused?
No. The Lap button is disabled while the watch is paused, so press Resume first. Time spent paused is never counted in any lap or in the running total.
When do the Fastest and Slowest labels appear?
Only with two or more laps, and they are recalculated after every new lap, so an earlier fastest lap can lose its label when a quicker one arrives.