Online Timer & Countdown
Last updated: June 2026 · Free · No sign-up required
Frequently Asked Questions
How does this online timer work?
This online timer uses standard browser APIs to run countdowns or track elapsed time locally on your computer. It features built-in preset times and a customizable alarm.
Does this timer require an internet connection once loaded?
No. Once loaded, the timer runs completely on your device using client-side JavaScript. You can use it offline.
Will the alarm sound if my screen goes to sleep?
Because the timer runs in your web browser, if your system suspends or goes into deep sleep mode, the JavaScript process might pause. To ensure the alarm triggers, adjust your device's energy savings settings to prevent sleeping while in use.
Quick reference
| Mode | Best for |
|---|---|
| Countdown | Cooking, exams, breaks, workouts |
| Stopwatch | Timing tasks, laps, experiments |
Interpretation guide
| Common timers | Setting |
|---|---|
| Soft-boiled egg | 6 min |
| Pomodoro focus | 25 min |
| HIIT round | 45 s work / 15 s rest |
| Exam section | Per paper — e.g. 35 min |
Formula & methodology
Formula: Countdown = target − now, ticked every 250 ms; stopwatch accumulates elapsed time with laps
- Pick countdown or stopwatch.
- Countdown: set hours/minutes/seconds and start — an audible alarm fires at zero, with the tab title ticking so you see it from other tabs.
- Stopwatch: start, lap and reset with millisecond display.
Worked example: a 25-minute countdown for a Pomodoro block rings on time even if you switch tabs — timing uses the system clock, not frame counting, so background throttling doesn’t drift it.
Frequently asked questions
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