Set the alarm clock for 3:39 am

 

Leave this tab open — the alarm only rings while the tab stays open.

The alarm goes off in: ::
 
 

Going to bed for a 3:39 am alarm

  • Asleep by 6:24 pm — 6 full sleep cycles, about 9 hours
  • Asleep by 7:54 pm — 5 full sleep cycles, about 7 hours
  • Asleep by 9:24 pm — 4 full sleep cycles, about 6 hours

A sleep cycle runs about 90 minutes, and most people take around 15 minutes to drop off. Waking at the end of a cycle feels easier than waking in the middle of one.

3:39 am across the country

Sydney3:39 am
Brisbane3:39 am
Adelaide3:09 am
Perth1:39 am
Darwin3:09 am

Times are worked out live in your browser, so daylight saving is already accounted for.

How to use the online alarm clock

Three in the morning has its own kind of silence, and an alarm for 3:39 am breaks it on purpose. Whether you're catching a pre-dawn flight or grabbing a short nap before a long haul, this tool rings at 3:39 am through your browser so you're not relying on a phone across the room.

After picking a tone, press Start and leave the page open. It doesn't need an internet connection once it's running, but it does need the tab itself to stay open, so avoid closing the browser or letting the device fall asleep before the time is reached.

This works well as a second alarm, one that isn't tangled up with phone notifications, do-not-disturb settings, or low battery. It genuinely won't ring if the tab gets closed or the device goes to sleep, so treat it as a backup or a work-desk tool rather than the only alarm for something important. On a 24-hour clock 3:39 am is written 03:39, and spoken aloud it's twenty-one minutes to four at night. Written the Australian way that's 3.39 am, and typed in a hurry it's often 3:39am. Set an alarm for 3:39 am, set the alarm to 3:39 am, set my alarm for 3:39 am — all of it lands on this page and does the same thing.

Common questions

Why use a browser alarm instead of my phone's built-in one?

Mainly for reliability against silent mode, do-not-disturb, or a phone left charging out of earshot. It's a useful backup or a desk-based alternative, though it depends on this tab staying open rather than running in the background of your phone.

Is there a cost to use this?

No, it's free, with no sign-up and no limit on how many times you set it. It just needs the tab left open until the time you've chosen arrives.

Will the alarm still ring if I close the browser tab?

No. The alarm only runs while this tab stays open — closing it, or closing the browser entirely, stops the countdown before it can ring. Keep the tab open in the background if you need it to go off later.

Does the alarm work if my laptop goes to sleep?

Not reliably. If the device sleeps or the screen locks, the browser tab pauses along with it, so the alarm may not fire on time or at all. Adjust your power settings if you're relying on this over a longer stretch.