Set the alarm clock for 10:21 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 10:19 am Alarm clock for 10:20 am Alarm clock for 10:22 am Alarm clock for 10:23 am

Going to bed for a 10:21 am alarm

Asleep by 1:06 am — 6 full sleep cycles, about 9 hours
Asleep by 2:36 am — 5 full sleep cycles, about 7 hours
Asleep by 4:06 am — 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.

10:21 am across the country

London	10:21 am
Birmingham	10:21 am
Manchester	10:21 am
Glasgow	10:21 am
Belfast	10:21 am

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

How to use the online alarm clock

While you wait to join the volunteer beach clean, an alarm for 10:21 am lets you follow the time without repeatedly checking the clock. There are 39 minutes before 11:00 am, enough to confirm the meeting point, gather gloves and prepare to leave without treating the round hour as your actual start time.

A beach-clean meeting point may be busy enough that the alarm needs a clear route to your attention. Check whether your phone has quietly sent browser audio to connected headphones, especially if they are packed in a pocket or bag. A quick sound check avoids discovering the connection only when the alarm is due. The beach-clean reminder will remain silent if the browser page is closed or the phone goes to sleep, so it should not be the only cue for setting off.

Before the beach-clean meeting time arrives, the changing morning light can affect what is useful to take. Placing sunglasses or a cap beside the gloves now keeps them visible if cloud gives way to glare before 10:21 am. Keeping the phone screen out of direct sunshine also makes the alarm controls easier to read when checking that it is still set.

Common questions

What happens if my laptop goes to sleep before 10:21 am?

The tab sleeps along with it and the alarm will not sound on time, if at all. If you are relying on it, change the power settings so the machine stays awake, or keep a phone alarm running as well.

Do I need an account or an app?

Neither. Choose a time and a sound, press Start, and it runs in this browser tab. Nothing is downloaded, nothing is registered, and closing the page leaves nothing behind on the device.

Can I change the sound?

Yes, there is a short list of tones to pick from before you press Start. Softer sounds are easy to sleep through, so a firmer bell tends to be the safer choice for anything early in the morning.

Will it still be right when the clocks change?

Yes. It reads your device's local clock, so the move between GMT and BST at the end of March and October is picked up automatically, as long as the computer's date, time and time zone are set correctly.