21 Minute Timer
Free online 21 minute countdown timer with alarm
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Customise colour, duration and size →Use in Google Docs or Canva →About the 21 Minute Timer
Set a 21 minute timer that shows its finish time before you commit, survives a throttled background tab, and alarms at zero. Optional ambient sound, fullscreen display, and push alerts if you close the tab.
TimerHub calculates remaining time from an absolute finish timestamp, so missed browser callbacks do not create drift. Read the timing accuracy methodology and reproducible tests.
Common Uses
- Pomodoro-length focus session
- Power nap
- Bodyweight workout
- Oven check while baking
- Timed quiz or test section
How to Use the 21 Minute Timer
- Press Start — or the Space bar — to run the 21 minute countdown. Space also pauses and resumes it; R resets it
- Adjust by 1 minute with the +/- buttons while it runs, toggle Repeat to loop it, and check the finish time shown under the display
- Use the Fullscreen control below the timer for a room-sized countdown (Esc to exit)
- Choose or mute the alarm in the header's sound settings, and pick a background sound — rain, ocean, fireplace or brown noise — that fades out at zero
- Enable notifications to be alerted when your 21 minute timer finishes in a background tab, and add
?autostart=1to the link to start the countdown on load
Frequently Asked Questions
How long is 21 minutes?
21 minutes is exactly 1,260 seconds, or 0.3 of an hour. Our free 21-minute timer counts down precisely and alerts you when time is up.
What can I do in 21 minutes?
A 21 minute timer is great for pomodoro-length focus session, power nap, bodyweight workout. Set it and focus on your task — the alarm will let you know when time is up.
Does the timer work in the background?
Yes, our timer continues running even if you switch to another tab or minimize your browser. Enable notifications to get alerted when it finishes.
Does the alarm sound when the timer finishes?
Yes, an alarm plays automatically the moment the 21 minute countdown reaches zero, with an optional vibration on mobile. Enable notifications for an extra system alert, even from a background tab.
Can I make the timer fullscreen?
Yes, use the Fullscreen control below the timer to expand the countdown to your whole screen — great for classrooms, presentations, and workouts. Press Esc to exit fullscreen.
Can I use the 21 minute timer on my phone?
Yes, our 21 minute timer is fully responsive and works on all devices including iPhone and Android. Open this page in your mobile browser and tap Start.