90 Minute Timer
A free 90 minute countdown timer. Used for the standard feature film, a football match, the complete ultradian focus cycle, and university double-lectures.
What is a 90 minute timer used for?
- ✓Deep work sessions (ultradian rhythm)
- ✓Long workshops and seminars
- ✓Extended study and revision
- ✓Film and lecture timing
How to use this timer
- 1Start the countdown
The timer is pre-set to 90 minute timer. Press the play button or hit Space to begin.
- 2Customise (optional)
Click the settings icon to change font, colour, background, and size. All settings are encoded in the URL — bookmark it to reuse your exact setup.
- 3Go fullscreen or add to OBS
Press F for fullscreen — ideal for classrooms and presentations. For streaming, enable transparent background and paste the URL into OBS as a browser source.
Frequently Asked Questions
Why do some people work in 90-minute blocks?
Research by Peretz Lavie and others shows the brain naturally cycles through 90-minute ultradian rhythms of high and low alertness. Working in 90-minute focused blocks and then resting aligns with this natural rhythm.
Why is 90 minutes the "ultradian" cycle?
Research on biological rhythms (Nathan Kleitman, 1953) identified roughly 90-minute cycles of alertness and rest in the human brain. The 90-minute work block matches the natural attention envelope; the BRAC (Basic Rest-Activity Cycle) is the underlying model.
Is 90 minutes the standard feature-film length?
Yes — 90 minutes is the post-1970s industry standard for theatrical features. Films routinely run 100–120 minutes, but distribution and pacing are still calibrated around the 90-minute reference.