Countdown Timer
Set a countdown timer with an alarm, in your browser.
The timer counts down in your browser and plays a sound when it reaches zero. Maximum is 99:59:59.
Recommended next steps
Related tools
Add or subtract two times in hours, minutes, and seconds.
Compute hours worked and pay between clock-in and clock-out.
Compute exact age in years, months, and days.
Frequently asked questions
Yes. The timer measures against a fixed end time rather than counting down a stored number, so even if your browser slows the tab down in the background, the remaining time stays accurate and finishes at the right moment when you return.
Yes. When the countdown hits zero you get an on-screen "Time's up" message and a short audible alarm. The sound is generated in your browser; some browsers only allow audio after you have interacted with the page, so pressing Start first ensures the alarm can play.
No. The countdown runs entirely in your browser using JavaScript. The duration you set and the timer itself never leave your device, and nothing is stored or uploaded.
You can set any duration up to 99 hours, 59 minutes, and 59 seconds. Larger entries are capped to that maximum, and minutes or seconds above 59 roll over into the next unit automatically.
Last updated 2026-06-23.