What a countdown is good for
A visible countdown changes behaviour in a way a deadline in a calendar does not. Two well-supported uses:
Timeboxing focused work
The Pomodoro technique runs 25 minutes of single-task work followed by a 5-minute break, with a longer break every four cycles. The value is not the specific number — it is that a running clock makes task-switching feel like a cost.
Timeboxing meetings and tasks
Parkinson's law — work expands to fill the time available — is why a visible timer shortens meetings. Setting 25 minutes rather than 30 tends to produce the same output with a buffer.
| Length | Used for |
|---|---|
| 2 min | The threshold below which a task is worth doing immediately |
| 5 min | Standup meetings, short breaks |
| 10 min | Warm-ups, quick reviews |
| 25 min | A Pomodoro focus block |
| 45 min | A deep-work session before attention drops |
| 90 min | One full ultradian cycle — the longest sustainable block |
How the timer keeps time
The countdown is driven by the system clock, not by counting ticks. That matters: a timer that increments a counter every second drifts, because browsers throttle timers in background tabs and each tick carries a few milliseconds of error.
This one records the target timestamp and computes the remaining time from the difference on every frame. Switch tabs, let your laptop sleep, come back — the reading is still correct.
Frequently asked questions
Does the timer keep running if I switch tabs?
Yes. It calculates the remaining time from the system clock rather than counting ticks, so background throttling does not cause drift.
The display catches up instantly when you return to the tab.
Will it alert me when it finishes?
It plays a short tone if the sound option is enabled and the tab is still open. Browsers block audio from closed or fully suspended tabs.
For an alarm you must not miss, use your phone.
Can I count down to a date years away?
Yes. Pick any future date and time — the display switches to days, hours, minutes and seconds automatically for longer spans.
Does it work offline?
Once the page has loaded, yes. Everything runs in your browser with no server involved.