How this timer works
This timer counts down from the duration you choose. The large digits show the remaining time, rounded up to whole seconds, in m:ss or h:mm:ss. In the readout strip, Status shows whether the timer is idle, running, paused or done. Set is the chosen duration; Ends is the expected finish time on your device's clock, shown in hours and minutes while the timer runs. Pause holds the remaining time, Start resumes it, and Reset stops the countdown and restores the last duration you set. At 0:00, use Reset or set a new time before starting again.
The countdown uses your device's clock. When you press Start, the page adds the remaining duration to the current time and saves that finish time. Each update subtracts the current time from it, rather than counting ticks, so a delayed update catches up with the clock. Start also requests audio playback through the browser's Web Audio API. When an update finds that time has run out, the digits show 0:00 and the panel changes color. The page then tries to play three short beeps.
Background tabs may update less often, and sleep or a locked screen can suspend the page. Both the display change and the chime can be late; there is no fixed maximum delay. While running, the timer requests a screen wake lock where supported, but browsers can refuse it and it only holds while the tab is visible. Keep the page open and visible, check the device's sleep settings before a long session, and use a separate alarm if missing the end would matter. The countdown follows your device's clock, including any changes to it; the page has no independent time source.
Frequently asked questions
Does the timer keep counting if I switch tabs or minimize the window?
Switching tabs does not pause the countdown. A hidden page may update less often or be suspended; when an update runs, it calculates the time left from your device's clock. If the finish time has passed, it shows zero and tries to play the chime then. The display and sound can be late, with no fixed maximum delay.
Why did my screen still dim or go to sleep?
The timer requests a screen wake lock while it runs, if your browser supports one. A wake lock only holds while the tab is visible, and the browser can refuse it because of battery-saving settings or device policy. It does not override a manual screen lock. Check the device's sleep settings before a long class block and keep this tab visible.
How do I set a time that isn't one of the presets?
Type a time in Custom, then press Set or Enter. Plain numbers are minutes: 7 means 7:00. Use 7:30 or 0:45 for minutes and seconds, or 1:30:00 for hours, minutes and seconds. Longer entries such as 90:00 work too. The first field accepts up to three digits for minutes or two for hours; each field after a colon must be 0–59. Zero or invalid entries leave the current countdown alone. A valid time stops any running countdown and loads the new duration; press Start to begin.
Why was there no sound when the timer ended?
The timer tries to play three short beeps when it detects the end. It cannot tell whether you hear them: device volume, speaker routing and browser audio permissions all matter. Try a short countdown before class. Treat the chime as an extra cue. When the timer updates after time runs out, the digits show 0:00 and the panel changes color, even if no sound plays. Sleep or a hidden tab can delay both signals.
Why is the Fullscreen button missing or not working?
The button is hidden when the browser lacks the fullscreen support this page needs. A browser that shows the button can still refuse the request. If that happens, the timer stays in its normal view. Fullscreen enlarges the timer panel and hides the preset and Custom controls. Leave with Esc where supported, or tap the on-screen Exit button.
