Start, pause and record laps. It follows the clock, so a background tab stays right.
The stopwatch does not count ticks. When you press Start it notes the time on your device clock, and every redraw works out how much time has passed since then. Pausing stores the time counted so far; resuming starts a new stretch and adds it to the stored amount. This is why the reading stays right when the tab sits in the background or the computer sleeps for a few minutes: the next redraw simply reads the clock again and shows the true total. The display is cut down, not rounded, so 1.999 seconds shows as 00:01.99. It shows minutes and seconds, and adds hours once you pass one hour. The stopwatch is only as good as the device clock. If the clock is changed by hand or by a time sync while the stopwatch runs, the reading changes with it, and a clock set backwards counts as no time for that stretch.
Lap records the running total at that moment. The lap time is the difference from the previous lap, or from zero for the first one, and the Total column is the running total. A lap needs time to have passed since the last one, so pressing Lap twice in the same instant records one lap. Once you have two laps the fastest lap time and the slowest are marked with the words Fastest and Slowest in the Note column, so the mark does not rely on colour. If every lap is exactly the same length nothing is marked, and when two laps tie for the fastest, the earlier one is marked. The table lists the newest lap first. The list holds up to 999 laps. After that the Lap button stays off until you reset. The Current lap tile shows the time since your last lap while the clock runs.
Space starts, pauses or resumes. L records a lap. R resets. The keys are ignored while the cursor is in a field or on a button, and when Ctrl, Alt or Command is held, so they do not clash with typing or with browser shortcuts. You can also use the buttons. Under Show you can choose seconds, tenths or hundredths of a second. That choice is remembered in this browser. Copy laps puts a tab-separated table on the clipboard with the header Lap, Lap time and Total, one line per lap in lap order, and the Fastest or Slowest word at the end of those lines. It pastes into a spreadsheet as columns. Where the browser supports it, the screen is kept on while the stopwatch runs; on other browsers it may dim.
Nothing you do here is saved or sent. The elapsed time and the laps live in this tab's memory. Reloading the page or closing the tab clears them, and a stopwatch that was running is lost, not continued. Only the precision choice is stored in this browser. Pausing keeps everything, so you can pause for an hour and resume. The page announces started, paused, resumed, lap and reset to screen readers, but never each tick of the display. Page visits are counted with Google Analytics, never your times. The stopwatch needs no connection once the page has loaded.
Yes. It counts from the device clock, not from the page redrawing, so when you come back the display jumps to the true total. A tab left in the background for 10 minutes shows 10 minutes more. The display may update less often while hidden, which does not change the final reading.
Yes. The time and the laps are held in this tab only, and a reload or closed tab clears them. Copy the laps before you leave. Only the precision setting is stored, so the page opens at zero every time.
Record at least two laps. The fastest lap time is marked with the word Fastest in the Note column, and the slowest with Slowest. The marks are words, so they work without colour. If all laps are the same length, nothing is marked.
It is exact to the millisecond the device clock reports, and shows seconds, tenths or hundredths of a second as you choose. The display is cut, not rounded, so it never reads ahead of the real time. Your own reaction time when pressing the button is usually larger than the stopwatch's error.
Yes. Space starts, pauses and resumes, L records a lap and R resets. They work when the cursor is not in a field or on a button. A phone has no such keys, so use the three buttons there.