About this tool
This page combines two everyday tools in one place: a countdown timer for any duration, and a stopwatch with lap-split recording. Both run using your device's system clock (not a simple tick counter), so they stay accurate even if the tab is backgrounded for a while.
How to use the Timer
- Enter minutes and seconds in the Minutes and Seconds boxes, or tap a quick preset (1, 5, 10, 15, 20, or 30 minutes).
- Tap Start — the display counts down live, and the browser tab title shows the time left.
- Tap Pause to hold the countdown and Start to carry on, or Reset to go back to the time in the boxes.
- A Time's up! alert appears when the timer reaches zero. In a background tab the alert can arrive late, so keep the tab visible for anything time-critical.
How to use the Stopwatch
- Open the Stopwatch tab at the top of the tool and tap Start to begin timing.
- Tap Lap while it is running to record the elapsed time without stopping the clock; the newest lap appears at the top of the list.
- Tap Reset to clear the time and lap list and start fresh.
Common use cases
- Timing a workout interval, a study session, or a cooking step
- Running a classroom activity or presentation within a set time limit
- Timing laps for a run, swim, or practice drill
- A quick countdown for a game, meeting icebreaker, or timed challenge
Things to watch out for
Browsers can throttle background tabs to save battery, particularly on mobile — for a critical countdown, it's safest to keep the tab visible or your device's screen on rather than relying entirely on a backgrounded alert. The tab title updates to show the remaining time as a visual cue even when the tab isn't active, which helps if you're glancing at browser tabs rather than the page itself.
Online stopwatch and online timer
This online stopwatch measures elapsed time with lap splits, and the online timer counts down from any length you set. Both run in your browser with no download or sign-up.
Timer techniques people use
A timer is useful for cooking, workouts, presentations and focus. The Pomodoro method uses 25 minutes of work followed by a 5-minute break, with a longer break after four rounds. For interval training, a common pattern is 30 seconds of effort and 30 seconds of rest. A stopwatch is better when you do not know how long something will take, such as timing a lap or a task you want to improve on.
How the timer keeps time
Instead of counting ticks, the countdown stores the moment it should end, taken from your device clock, and checks it four times a second. Each check subtracts the current time from the end time and shows what's left. The stopwatch does the reverse: it stores when you pressed Start and shows the time since then, updating ten times a second. Because the display is always recalculated from the clock, a missed or delayed update doesn't make the time drift; the next update catches up.
Two display details follow from this. The countdown rounds up to the next whole second, so it shows 05:00 until a full second has passed and reads 00:00 only when time is really up. The stopwatch shows minutes, seconds and tenths, and keeps counting minutes past 60, so an hour and a half reads 90:00.0. For longer countdowns, type any number of minutes up to 999; a 90-minute timer is simply 90 in the Minutes box.
Why the alarm can arrive late in a background tab
Browsers slow down timers in tabs you aren't looking at, to save power. MDN documents that Firefox runs timers in inactive tabs at most once per second, and that Chrome, after a page has been hidden for more than five minutes and has been silent, can check timers only once per minute. The time left stays correct, because it comes from the clock, but the moment the tool notices the countdown has finished, and shows the alert, can be delayed. Mobile browsers may pause or unload background tabs entirely.
For anything where lateness matters, such as cooking or a test, keep this tab visible, or at least in its own window that isn't minimized, and keep the screen on. The tab title shows the remaining time while the countdown runs, so you can glance at it from another tab.
Reading lap times
Each lap shows the total elapsed time at the moment you pressed Lap, not the length of that lap alone. The newest lap appears at the top of the list. To get an individual lap's duration, subtract the previous lap's time: if Lap 1 reads 01:12.4 and Lap 2 reads 02:20.1, the second lap took 1:07.7. For adding or subtracting longer spans of time, the Time Duration Calculator does the arithmetic for you.
Because both tools read your device clock, changing the system time while one is running, or an automatic clock correction, can make the reading jump. Counting down to a calendar date instead? Use the Countdown to Date tool.
Frequently asked questions
Yes. The countdown keeps tracking the time from your device clock in a background tab, and a pop-up alert reading Time's up! appears when it reaches zero. While it runs, the tab title shows the time left; at zero the title goes back to the normal page name. The alert can be delayed in a background tab, so keep the tab visible when the exact moment matters.
Yes. While the stopwatch is running, each press of Lap records the elapsed time, and the laps are listed below the stopwatch with the newest at the top.
It's accurate to the second for practical purposes, using your device's system clock rather than a simple counter, so it won't drift even if the tab is in the background for a while.
Browsers throttle timers in background tabs to save power. Chrome can check them only once a minute after a tab has been hidden for five minutes, so the alert may come late even though the remaining time was tracked correctly. Keep the tab visible and the screen on when the exact moment matters.
Each lap entry is the total time on the stopwatch when you pressed Lap, and the newest lap is listed first. To find how long a single lap took, subtract the previous entry from it. For example, 02:20.1 minus 01:12.4 means that lap took 1 minute 7.7 seconds.
Yes. Type the whole duration in minutes, up to 999, into the Minutes box and press Start. A 90-minute timer is 90 minutes and 0 seconds, and a two-hour timer is 120 minutes. The display shows the countdown in minutes and seconds, so two hours starts at 120:00.
No. The stopwatch has Start, Lap and Reset buttons only, so once started it keeps counting until you press Reset, which clears the time and every lap. If you need to pause and resume, use the Timer tab, whose Pause button holds the remaining time until you press Start again.