Timer and stopwatch
Count down a chosen interval or measure elapsed time with pause, resume and lap records. Keep the tab open to see the completion message.
Choose countdown or elapsed time
Timer mode starts from the number of minutes and seconds entered in the controls. Stopwatch mode starts from zero and measures elapsed time. Select the mode before starting. A change of mode resets the current measurement and clears lap records, so copy any useful lap values before switching. The display uses hours, minutes, seconds and hundredths of a second; displayed precision is not a claim of laboratory timing accuracy.
Start, pause and resume
Press Start / resume to begin. Pause freezes the current elapsed amount and Resume continues from that amount. Reset stops the session, returns the stopwatch to zero or the timer to its selected duration, and clears the lap list. Timer inputs accept whole minutes from zero to 1,440 and whole seconds from zero to 59. A zero-length timer cannot start. Change the duration while stopped, then reset before starting another interval.
Example: a five-minute review
Leave Timer selected, enter five minutes and zero seconds, then start. Pause if the review is interrupted and resume when ready. At zero the page displays a completion message and the countdown stops. There is no sound, notification permission request or operating-system alarm. This is useful for a visible on-screen interval, but it should not replace an alarm that must be heard while another app is in use.
Record stopwatch laps
Choose Stopwatch, start the measurement and press Lap at each milestone. Each record shows total elapsed time from the start, including earlier running periods and excluding paused time. A lap is not the difference from the preceding record. Up to 100 records are kept in the current page session, with the newest first. Reset, mode changes, a page refresh or closing the tab removes those records.
How browser timing affects the display
Elapsed time is calculated from performance.now() instead of counting interval callbacks. This reduces drift caused by delayed screen updates while the page is active. Background tabs, power saving, device suspension and browser process termination can still delay updates or interrupt the session. Behavior during system sleep varies by platform. Keep the page visible for timing that needs immediate observation, and check the device clock independently for critical deadlines.
Questions and limits
Can a session be restored after refresh? No, the current implementation keeps state only in page memory. Is it suitable for official race timing, medication schedules or unattended safety alarms? No; browser scheduling and device sleep make those uses unsuitable. Are durations sent to a timing server? The timing calculation runs in this browser. Other site resources may load normally, but no separate timing service is used to calculate the session.