Countdown Timer
A big fullscreen countdown timer with presets, pause and resume, and a sound and visual alert.
Quick answer
What is the Countdown Timer?
A countdown timer counts down from a set time to zero in large fullscreen digits, then alerts you with a gentle flash and an optional chime. Set hours, minutes and seconds for classes, exams, meetings, presentations, workouts or cooking, and read it clearly from across the room.
Key features
- Big fullscreen digits
- Hours, minutes and seconds input with presets
- Screen flash and optional chime at zero
- Keeps time accurately even in background tabs
Why use it
- Keeps meetings and classes on schedule
- Readable from the back of a room
- Free, no app
Built and tested by Whitson Rao
About the Countdown Timer
A large, readable countdown timer for classrooms, presentations, workouts and cooking. Set any duration, use presets, and get a visual and optional sound alert when time is up.
Why the timer stays accurate
The countdown is measured against the system clock and an end time, not by counting ticks. If your browser slows down a background tab, the remaining time is still correct when you come back, and the alert still fires on time.
When time is up you get a clear visual change and an optional chime, so it works in noisy rooms and silent ones.
Ideas for using a fullscreen countdown
Use it for presentations and speaking slots, exams and classroom activities, cooking, workouts, meetings that must end on time, or a 'starting soon' screen on a stream. For repeated work and break cycles, the Pomodoro Timer switches phases for you, and the Stopwatch counts up when there is no fixed limit.
How to use the Countdown Timer
Choose a preset such as 1, 5 or 25 minutes, or type hours, minutes and seconds.
Press Start or Space. Press Space again to pause, or R to reset.
Turn on the chime if you want a sound — it is off by default.
Press F for fullscreen so the whole room can see it. Press Esc to exit.
Common uses
Classrooms
Time tests, activities and breaks on a projector.
Presentations
Keep speakers on schedule with a visible timer.
Pomodoro
Run 25-minute focus sessions with short breaks.
Workouts & cooking
A big timer you can read from across the room.
Frequently asked questions
Does the timer keep running in a background tab?
Yes. It is based on the actual clock time, so it stays accurate even if the browser slows down background tabs.
Will it make a sound?
Only if you turn on the chime. Otherwise the screen flashes gently when time is up.
What is the maximum duration?
You can set up to 99 hours, 59 minutes and 59 seconds.