Set the alarm clock for 5:21 am

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

The alarm goes off in: ::

You can also try the other alarm clocks

Alarm clock for 5:19 am Alarm clock for 5:20 am Alarm clock for 5:22 am Alarm clock for 5:23 am

Going to bed for a 5:21 am alarm

Asleep by 8:06 pm — 6 full sleep cycles, about 9 hours
Asleep by 9:36 pm — 5 full sleep cycles, about 7 hours
Asleep by 11:06 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.

5:21 am across the country

Sydney	5:21 am
Brisbane	5:21 am
Adelaide	4:51 am
Perth	3:21 am
Darwin	4:51 am

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

How to use the online alarm clock

Tradies, nurses on night shift, and anyone driving to the airport before the birds wake up all end up here around 5:21 am. This alarm rings straight from your browser tab at 5:21 am, loud enough to cut through a quiet house, without needing an app or an account first.

There's a short list of sounds to choose from before you press Start — pick one that suits how deep a sleeper you are. Once it's set, the page keeps time in the background of your browser, and it'll sound at the moment you selected, provided the tab hasn't been closed.

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 5:21 am is written 05:21, and spoken aloud it's twenty-one minutes past five in the morning. Written the Australian way that's 5.21 am, and typed in a hurry it's often 5:21am. If you need it loud, turn the system volume up before you start: the alarm plays at whatever the device is set to.

Common questions

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.

Do I need to create an account or download anything?

No, there's nothing to sign up for and nothing to install. Pick a time and a sound, press Start, and it runs entirely in this browser tab.

Can I change the alarm sound?

Yes, there's a short list of tones to choose from before you press Start. Pick whichever one you're most likely to actually hear — softer sounds are easier to sleep through than a firm chime or bell.

What happens once the alarm goes off?

It rings through your device's speakers on a loop until you stop it from this page. There's no separate app notification, so make sure your volume is turned up before you rely on it.