Run a live countdown timer from a duration you specify in years, months, weeks, days, hours, minutes, and seconds. The display ticks down to zero using the browser clock so you can track remaining time for exams, cooking, meetings, or event launches without installing a separate timer app.
How it works
Inputs are converted into a total duration in seconds, then a client-side interval subtracts elapsed wall-clock time and formats the remainder as padded clock fields (and optional higher units). When the remaining seconds reach zero, the timer stops at the finished state. Resource cleanup clears intervals when the component unmounts so background tabs do not leak timers.
When to use it
- Classroom or exam time boxes with a visible remaining clock
- Kitchen or workout intervals longer than a phone’s quick timer UI
- Event “opens in …” displays during rehearsals
Limitations
Browser timers can drift under heavy load or when the tab is throttled in the background; do not rely on this for safety-critical or legal deadlines. Calendar months/years are converted as fixed duration units for the countdown, not as civil calendar arithmetic to a specific date. System sleep suspends JavaScript timers until resume.
Example
A duration of 0 years, 0 months, 0 weeks, 0 days, 1 hour, 30 minutes, 0 seconds starts at 01:30:00 on the clock display and reaches 00:00:00 after ninety minutes of continuous foreground running.