90-Minute Timer
Press start. It counts down to zero and rings an alarm — nothing to download, nothing to sign up for.
About this 90-minute timer
A one-click 90-minute countdown, most often used for a sleep cycle nap, a deep-work block, or a long exam simulation. It runs in your browser and rings when it reaches zero.
One full sleep cycle
Ninety minutes is roughly one complete sleep cycle, moving through light sleep, deep sleep, and REM before returning to light sleep. Waking at the end of a cycle rather than the middle of one is why a 90-minute nap can leave you refreshed while a 45-minute one leaves you fuzzy. It's also the length researchers associate with a single sustained block of deep, focused work.
90 minutes in other units
| Seconds | 5,400 |
|---|---|
| Minutes | 90 |
| Hours | 1.5 |
| Milliseconds | 5,400,000 |
| Share of a day | 6.25% |
Tips for using a 90-minute timer
- If you nap longer than 20 minutes, aim for the full 90 so you wake at the end of a cycle rather than mid-deep-sleep.
- Ultradian rhythm research suggests the body works in roughly 90-minute cycles of alertness — a natural deep-work block.
- Ninety minutes is a football match, which makes it a familiar mental yardstick for a long stretch.
Frequently asked questions
How do I set a 90-minute timer?
Press Start above and the page counts down from 90 minutes on its own — nothing to type. Need a little longer? Press +1 min while it runs, or pick a nearby duration from the list.
How many seconds are in 90 minutes?
90 minutes is 5,400 seconds — 90 minutes or 1.5 hours. That's 6.25% of a day.
What is a 90-minute timer good for?
People commonly use a 90-minute timer for a sleep cycle nap, a deep-work block, or a long exam simulation.
Will it keep time if I switch tabs?
Yes. The countdown is measured against your device clock rather than counting screen refreshes, so it stays accurate in a background tab and the alarm fires on time. For a timer this long, keep the device awake — some phones pause browser audio when locked.