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Stopwatch

Online stopwatch that shows hundredths of a second, records laps with the fastest and slowest marked, and keeps the time in your browser if you reload the page. How it works

Use the Stopwatch

00:00.00

L records a lap; Space starts or stops once you click the time display or Tab to the stopwatch. Timing follows your device's clock; if the clock is changed while the stopwatch runs, the reading changes with it.

The time and laps are kept in this browser, so a reload does not lose them; a running stopwatch keeps counting while the page is closed.

About the Stopwatch

This online stopwatch counts in hundredths of a second (01:23.45), records lap times and keeps running if you reload or close the page. Stop and Lap read the device’s clock at the moment you click, so a slow or background tab does not lose time.

How to use this tool

  1. Press Start.
  2. Press Lap each time a lap ends. The clock keeps running.
  3. Press Stop to pause. Start resumes from the same time.
  4. Press Copy laps to copy the lap list as text, or Reset to clear the time and the laps.
  5. Press Fullscreen, or F, to fill the screen with the time and the buttons where the browser allows it. Esc or Exit fullscreen returns.

Frequently asked questions

How accurate is an online stopwatch?
The stopwatch reads the device’s clock, which browsers report in whole milliseconds, and shows hundredths of a second. Elapsed time is the time now minus the time you pressed Start, so it is as steady as that clock. What limits a hand-timed result is how quickly you press the button.
Does the stopwatch keep running if I close the tab?
Yes. The start time is stored in your browser, so when you open the page again the stopwatch shows the full time since you pressed Start, including the time the page was closed. Stopped times and laps are kept too. Reset or Clear Saved Values stops a running stopwatch and clears it, and one left running stops by itself at 1,000 hours.
Does it show milliseconds?
No. It shows hundredths of a second, rounded down, as minutes:seconds.hundredths. After one hour the format becomes hours:minutes:seconds.hundredths, for example 01:02:03.45.
How do I record lap times?
Press Lap while the stopwatch runs. Each lap is listed with its own time and the total so far, newest first. Up to 1,000 laps are kept, and Copy laps copies them as plain text.
Does it work in a background tab?
Yes. Browsers slow the on-screen updates of a hidden tab, but the elapsed time is read from the clock when you come back or press Stop, so nothing is lost. You can switch tabs, lock the phone or close the page and the count carries on.
Are there keyboard shortcuts?
Space starts and stops, L records a lap, and F turns fullscreen on and off where the browser supports it. L and F work while focus is anywhere in the stopwatch, including on its buttons. Space works while the stopwatch itself has focus, so click the time display or Tab to it first; on a button Space presses that button as usual. In the lap list neither key is handled, so Space scrolls the list.

Reading the lap table

Press Start and the display counts minutes, seconds and hundredths of a second (01:23.45), adding hours once it passes 60 minutes. Lap records the lap just finished without stopping the clock. Stop pauses, Start resumes from the same time, and Reset clears the time and the laps.

Each row of the lap table holds two numbers: the lap time, which is how long that one lap took, and the total, which is the stopwatch reading when you pressed Lap. The newest lap is at the top. Fastest and Slowest appear once there are two laps with different times, so on a 400 m track session or a set of gym intervals you can see at a glance which repeat dropped off. Copy laps puts the list on the clipboard as text for a spreadsheet or a training log. Fullscreen, or the F key, fills the screen with the time and the buttons where the browser allows it, so the clock reads from across a gym or a classroom; Esc or Exit fullscreen returns.

The time and laps are stored in this browser, so a reload does not lose them, and a stopwatch left running keeps counting while the page is closed. Clear Saved Values removes them.

How the time is measured

The stopwatch does not count ticks. Elapsed time is worked out from the device's clock: the time now minus the time the stopwatch was started. Stop and Lap read that clock when the click or key press arrives. A busy page or a background tab can delay the picture on screen, but not the time recorded.

The display shows hundredths of a second, rounded down: 83,459 milliseconds reads 01:23.45. A lap time is that lap's total minus the previous lap's total. Pressing Lap at 01:02.31, 02:01.87 and 03:05.02 gives laps of 01:02.31, 00:59.56 (fastest) and 01:03.15 (slowest).

Limits: 1,000 laps and 1,000 hours. A running stopwatch stops by itself when it reaches 1,000 hours.

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