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

London	5:21 am
Birmingham	5:21 am
Manchester	5:21 am
Glasgow	5:21 am
Belfast	5:21 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 watch the clock before opening the public pool for its early session, set the alarm for 5:21 am so the appointed moment does not slip past. There are still several opening tasks that can fit before 6:00 am, but keep them short enough that you can stop as soon as the signal sounds.

Pool preparations can create more background noise than expected, especially with ventilation running, water circulating and equipment being moved. Set your phone or computer volume high enough to hear the alarm from your working position, then test the sound before continuing. Keep the speaker uncovered and avoid leaving it in a staff room if you will be beside the pool. Do not rely on this alarm alone for the pool opening: it cannot sound after its page has been closed or when your phone or computer has gone to sleep.

Reaching the pool before dawn may be quicker on quiet roads, though roadworks, overnight closures and reduced early bus services can still alter the journey. Check the route before leaving, allow a small buffer beyond the usual travel time, and note whether the entrance or staff car park uses a different access point at this hour.

Common questions

What happens if my laptop goes to sleep before 5:21 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.