Set the alarm clock for 4:20 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 4:18 am Alarm clock for 4:19 am Alarm clock for 4:21 am Alarm clock for 4:22 am

Going to bed for a 4:20 am alarm

Asleep by 7:05 pm — 6 full sleep cycles, about 9 hours
Asleep by 8:35 pm — 5 full sleep cycles, about 7 hours
Asleep by 10:05 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.

4:20 am across the country

Sydney	4:20 am
Brisbane	4:20 am
Adelaide	3:50 am
Perth	2:20 am
Darwin	3:50 am

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

How to use the online alarm clock

Setting an alarm for 4:20 am while everyone else is asleep can feel like cheating the clock, but it's usually just planning ahead for an early departure or a shift that starts before sunrise. This will sound at 4:20 am through your speakers, whether it's the depths of winter or a short summer night.

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 4:20 am is written 04:20, and spoken aloud it's twenty past four at night. You'll also see it written 4.20 am — a full stop instead of the colon means the same time. Setting the alarm to 4:20 am tomorrow morning works the same way: if the time has gone for today, the count runs through to it.

Common questions

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.

Is this alarm accurate across daylight saving time?

It uses your device's local clock, so as long as your computer's time and date settings are correct, it'll adjust automatically when daylight saving time starts or ends.

Can I use this on my phone instead of a laptop?

Yes, it works in a mobile browser the same way, but phones are more likely to lock the screen or sleep, which can stop the alarm from ringing. A laptop or desktop tends to be more reliable for this.

Can I set more than one alarm at a time?

This page is built around a single alarm at a time. For multiple alarms, open a separate tab for each one and set a different time in each, keeping every tab open until it's rung.