90 Minute Classroom Timer
Free online 90 minutes classroom with alarm sounds, repeat mode, and browser notifications. No sign-up, no ads.
A 90 minutes classroom timer keeps lessons on track. 90 minutes is deep session — mastery sessions, extended workshops, and ultradian rhythm alignment. Perfect for timed activities, tests, and transitions.
Project this timer on a screen so the whole class sees the same countdown. Use it to structure transitions, timed writing, and group rotations. The visual ring helps students self-pace without constant reminders.
Lesson ideas
FAQs
Can I project this on a screen?
Yes. Fullscreen mode (F key) hides the UI for clean projection.
Can students see it on their devices?
Share the URL — it works on any device with a browser. No app install needed.
What can you actually do in 90 minutes?
A full workout class, a university lecture, a coding sprint, a slow-cooked meal prep, or a deep meditation session. 90 minutes is the goldilocks zone for deep work.
How accurate is a 90-minute countdown?
The timer counts milliseconds. For a 90-minute count, it’s within a fraction of a second — accurate enough for any session.