Countdown Timer & Stopwatch
Count down to a specific date and time or a set duration — with a sound alert, live tab-title countdown, and full-screen display — or track elapsed time with a stopwatch and lap splits.
How to Use the Countdown Timer & Stopwatch
- Choose "Countdown Timer" or "Stopwatch" from the pill toggle at the top.
- For the countdown timer, pick "Duration" or "Specific Date & Time", then set the hours/minutes/seconds or the target date and time.
- Click "Start" — use "Pause"/"Resume" and "Reset" to control it, and leave "Play a sound when the countdown finishes" checked to hear a chime at zero.
- Click "Full-Screen Display" for a large, distance-friendly view, and check the browser tab title for a live countdown even while you're on another tab.
- For the stopwatch, click "Start" to begin timing, "Lap" to record a split without stopping, and "Reset" to clear.
- Watch the large display update live; the countdown timer alerts "Time's up!" and plays a chime (if enabled) when it reaches zero.
Frequently Asked Questions
Does the countdown timer keep running if I switch to another browser tab?
Yes — the timer tracks the actual end time using the system clock rather than just counting down a fixed number of ticks, so it stays accurate even if the tab is backgrounded or the browser throttles JavaScript timers.
What do the numbers in parentheses mean next to each lap in the stopwatch?
Each lap shows the split time (time since the previous lap) first, followed by the total elapsed time in parentheses — so you can see both how fast that segment was and your overall running time.
Can I set a countdown for more than 24 hours?
Yes, the Hours field accepts any number, not just 0-23, so you can set very long countdowns, like 48 hours, if needed.
Will the timer or stopwatch keep running if I close the browser tab?
No — both run entirely in your browser and reset once the page or tab is closed; there's no background or server-side timer, so keep the tab open while it counts.
What happens if I click Start on the countdown timer without setting a duration?
If the total duration is zero, the tool shows a message asking you to set a duration greater than zero instead of starting.
Can I count down to a specific date and time instead of just a duration?
Yes — switch the countdown timer to Specific Date & Time mode, pick any future date and time with the date-time picker, and the timer counts down to that exact moment using the same clock-based math as duration mode, so it never drifts.
Does the countdown timer make a sound when it finishes?
Yes — with the Play a sound when the countdown finishes option checked, the timer generates a short chime using the Web Audio API the instant it reaches zero, so there's no audio file to download. Uncheck the option to finish silently.
Can I check the remaining time without switching back to this tab?
Yes — while the countdown is running, the browser tab's title updates every quarter second to show the time remaining, so you can glance at the tab bar to check progress without switching back to the page.
Is there a big, full-screen display mode for the countdown timer?
Yes — click Full-Screen Display to enlarge the timer to fill your screen, which is useful for presentations, classrooms, or viewing from across a room. Click Exit Full-Screen or press Esc to return to the normal view.
What happens if I pick a date and time that's already in the past?
The display shows 00:00:00, and clicking Start shows a message asking you to pick a date and time in the future instead of starting a countdown that has already finished.