Lite Tools

Countdown Timer

Precise online countdown timer with end alert. Set hours, minutes and seconds, watch the time tick down, and get alerted when time is up.

00:05:00

Note: browsers throttle timers in background tabs, so keep this page open and in the foreground during the countdown to ensure an on-time alert.

How to use

  1. Enter the target duration in the Hours / Minutes / Seconds fields, or tap one of the 1 / 5 / 10 / 25 minute quick presets.
  2. Click "Start" to begin. While running, the button turns into "Pause" so you can pause and resume anytime.
  3. During the countdown, the browser tab title shows the remaining time in real time: handy when you have many tabs open.
  4. When time is up, the page plays a beep and shows "Time's up!". Click "Reset" to go back and set a new duration.
  5. On-time alerts rely on the page running, so keep it open and in the foreground.

FAQ

Is the countdown accurate?
Yes. The timer computes the difference between a fixed end timestamp and the current time instead of counting interval ticks, so jitter in the timer never accumulates into drift. As long as the page runs, the remaining time stays exact.
What happens if I switch to another tab?
Browsers throttle timers in background tabs and may even pause them under power-saving modes, which delays the end alert. Keep this page in the foreground; when you come back, the remaining time is corrected immediately.
No sound or vibration when time is up?
Browsers only allow audio after a user interaction, so click "Start" first. If audio is still unavailable, devices that support vibration fall back to it automatically. You can also try Chrome, Edge or Firefox.
What is the maximum duration?
The hours field accepts up to 99, so the longest countdown is 99 hours 59 minutes 59 seconds: enough for cooking, studying, working or workouts.

How to use

  1. Set hours, minutes, seconds

    Type values into the Hours, Minutes and Seconds fields, up to 99 hours. Or tap the 1, 5, 10 or 25 minute preset chips to fill them instantly.

  2. Start the countdown

    Press Start and the large digits plus the progress bar tick down together. The button turns into Pause, and Reset returns everything to the setup state.

  3. Watch the tab title

    While running, the browser tab title shows the remaining time in real time. A glance at your tabs tells you how long is left.

  4. React to the alert

    When time runs out the page plays a beep, shows the Time's up message and vibrates on capable devices. Click Reset to set a new duration.

  5. Keep the page up front

    Browsers throttle timers in background tabs, so keep this page in the foreground for punctual alerts. After switching away, the readout corrects itself on return.

About this tool

This countdown timer computes the difference between a fixed end timestamp and the current time, instead of counting interval ticks. Timer jitter never accumulates into drift, and the remaining time stays exact. Durations combine hours (0-99), minutes and seconds, displayed with a progress bar and monospaced digits. When time is up, a beep, an on-page message and device vibration fire together.

Use it for kitchen timing, workout intervals, classroom drills, meeting timeboxes or any deadline outside a Pomodoro routine. Entering 90 in the seconds field alone covers a short plank hold. A zero total raises a prompt to set a duration first. The running tab title mirrors the remaining time, so progress stays visible even with many tabs open.

How it works

A browser's setInterval never promises exact spacing. Every callback queues behind the event loop, so one late tick pushes every later tick late as well. A countdown built on subtract one per tick can drift minutes in a day. This timer records a fixed end timestamp instead and computes remaining time as end minus now on every refresh. Jitter therefore never accumulates, and the readout still matches the clock after any stall. The time source matters too. Date.now() is a wall clock that jumps when the system resyncs, while performance.now() is a monotonic clock that only moves forward. The monotonic one is what a timer should trust.

Background tabs get throttled. Chrome clamps timers in tabs hidden for more than five minutes to one run per minute, and power-saving modes tighten that further. That is the root cause of an alarm arriving late. When the page returns to the foreground the visibilitychange event fires, and the tool recomputes remaining time from the timestamp. The readout self-corrects without a manual refresh. Mirroring the countdown in the tab title extends the same idea. Title updates are throttled as well, but timestamp math guarantees whatever is shown is correct, merely possibly shown a beat late.

When to use it

  1. Hands-free kitchen timing

    When the phone is greasy, leave the countdown on a tablet or laptop. Set three minutes, press Start, and read the digits from across the stove. The beep watches the pot so your hands keep prepping.

  2. Classrooms and talks

    Put a 10-minute countdown on the projector. The audience watches the bar drain, and the speaker never needs a moderator waving cards. Switch the lectern computer to slides and the tab title still shows the time left.

  3. Rest intervals in training

    A 90-second plank and a 60-second rest each get a round. Hit Pause when a call arrives, Continue to pick the count up, and Reset to zero the digits and the bar for the next set.

Tips & tricks

  • Browsers allow audio only after you interact with the page, so click Start once even if you plan to mute later.
  • For short spans like 90 seconds just fill the seconds field. A zero total triggers a setup prompt instead.
  • For long countdowns glance at the tab title occasionally rather than relying on the alert alone.

Things to watch

  • Field limits on duration

    Hours cap at 99, and minutes and seconds each have their own valid range. A 100-minute countdown belongs as 1 hour 40 minutes. Invalid values are rejected with a hint. For multi-hour spans a date-based countdown tool fits better.

  • Closing the page clears the timer

    The running state lives in memory, so a refresh or a closed tab returns everything to zero. The setup must be redone after that. For long-running reminders keep the tab open and pinned somewhere an accidental close is unlikely.

  • The fallback when audio fails

    With the system muted or audio unsupported the beep is silent, while the on-page message and vibration still fire. Never bet a deadline on sound alone. The emptied progress bar and the Time's up text are the backstop.

Related Tools