Ninety minutes matches one full sleep cycle and one ultradian focus cycle — which is why it shows up in both nap advice and deep-work planning. Starts automatically.
Human alertness moves in roughly 90-minute ultradian cycles, and a full sleep cycle runs about the same length. Both facts make 90 minutes a natural boundary for rest and for concentrated work.
Ninety minutes is one complete sleep cycle through light, deep and REM sleep — which is why a 90 minute nap leaves you clearer than a 60 minute one, despite being longer. It is also a full football match, a short feature film, and about 7.5 kilometres of steady walking.
Useful when a recipe, workout plan or exam paper states the time differently:
| 90 minutes in… | Value |
|---|---|
| Seconds | 5,400 |
| Minutes | 90 |
| Hours (decimal) | 1.5 |
| Fraction of an hour | 3/2 hours |
| How many fit in an hour | less than one |
| How many fit in a day | 16 |
This page starts the 90 minutes for you automatically. Leave the tab open and carry on with something else; VClock keeps counting in the background and alerts you at zero with sound, a flashing display and a changed tab title. Use Pause if you need to interrupt it.
You can change the alarm sound at any point before or during the countdown — Beep, Digital, Alarm Bell, Chime, Siren and Soft Wake are all available, and each plays a short preview when selected. To use a different length, press Reset and type any duration, or pick one from the main timer page.
Need something else? Try a little shorter with the 1 hour timer or a little longer with the 2 hour timer. For a round comparison, exactly half this length is the 45 minute timer.
Ninety minutes completes a full sleep cycle, so you wake during light sleep. Sixty minutes tends to wake you mid-deep-sleep, producing the heavy grogginess known as sleep inertia.
Some people can, particularly on absorbing creative work. If your attention fades around the hour mark, that is normal — try the 50 minute timer and build up.
Yes — the countdown begins as soon as the page loads, so there is nothing to press. If you would rather start it yourself, press Reset and then Start.
Yes. Pause holds the remaining time exactly where it is; Resume continues from that point and Reset returns the clock to the full 90 minutes.
VClock plays your selected alarm sound on a loop, flashes the display and changes the browser tab title. Press Stop Alarm to silence it.
Completely. There is no sign-up, no download, no daily limit and no watermark — set it as many times as you like.
Switch to the VClock alarm clock to ring at a specific hour instead of counting down.
Open the Alarm Clock