90-Minute Timer
Ninety minutes is one full sleep cycle, which makes it the length to plan a nap around — waking at the end of a cycle rather than the middle leaves you far less groggy. It is also a natural ceiling for deep, undistracted work: research on ultradian rhythms suggests focus runs in roughly 90-minute waves before it needs a real break. Use it for a long study or work block, an extended workout, or a nap timed to land between sleep cycles.
90 min
JavaScript is required to run this timer — enable it to start, pause, and hear sound alerts.
This finished while this tab wasn't open to notice — we can't alert a closed tab, only report back honestly like this.
Space start/pause R reset F fullscreen
Enable JavaScript to see background-alert options — this timer keeps correct time either way, but notifications and the install prompt both require it.
Frequently asked questions
- Why time a nap for 90 minutes?
- A full sleep cycle is roughly 90 minutes. Waking at the end of a cycle, rather than being pulled out of deep sleep partway through, tends to leave you feeling far more rested than a random longer nap.
- Is 90 minutes a good length for focused work?
- Many people find focus comes in cycles of around 90 minutes (an "ultradian rhythm") before concentration drops and needs a genuine break. A 90-minute deep-work block followed by rest is a common way to structure demanding work.
- Will the alarm fire if the tab is in the background that long?
- The end time is tracked accurately over any gap, so the finished state is always correct when you return. But over 90 minutes a backgrounded or closed tab may not sound at all — for a reliable alarm, keep the tab open, and on iPhone keep the mute switch off.
This timer keeps the exact time even if you switch tabs. If this tab or your browser closes, nothing can alert you at the exact finish time — there's no server behind this, by design. Come back any time and we'll tell you honestly how long ago it ended.