Set the alarm clock for 3:40 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 3:38 am Alarm clock for 3:39 am Alarm clock for 3:41 am Alarm clock for 3:42 am

Going to bed for a 3:40 am alarm

Asleep by 6:25 pm — 6 full sleep cycles, about 9 hours
Asleep by 7:55 pm — 5 full sleep cycles, about 7 hours
Asleep by 9:25 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.

3:40 am across the country

Sydney	3:40 am
Brisbane	3:40 am
Adelaide	3:10 am
Perth	1:40 am
Darwin	3:10 am

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

How to use the online alarm clock

An alarm for 3:40 am is usually about catching something before the rest of the world is awake: a ferry, a flight, or a change of shift. Set the time, pick a tone, and leave this tab open. At 3:40 am it'll ring through your device's speakers until you tell it to stop.

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.

A browser alarm like this one is handy when your phone's on silent, charging in another room, or you just don't want to unlock it and get pulled into notifications. The trade-off is honesty: it only rings while this tab stays open, so it's not a replacement for your phone alarm on a trip where the laptop lid might close. On a 24-hour clock 3:40 am is written 03:40, and spoken aloud it's twenty to four at night. Timetables and rosters may show it as 03:40, and handwritten notes as 3.40 am. 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

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.

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.