Set the alarm clock for 7:35 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 7:33 am Alarm clock for 7:34 am Alarm clock for 7:36 am Alarm clock for 7:37 am

Going to bed for a 7:35 am alarm

Asleep by 10:20 pm — 6 full sleep cycles, about 9 hours
Asleep by 11:50 pm — 5 full sleep cycles, about 7 hours
Asleep by 1:20 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.

7:35 am across the country

London	7:35 am
Birmingham	7:35 am
Manchester	7:35 am
Glasgow	7:35 am
Belfast	7:35 am

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

How to use the online alarm clock

As you hand responsibility for meeting the sunrise on Snowdon to someone else, set the alarm for 7:35 am and make the handover explicit: who is waking, who is checking the route, and who has the shared kit. That leaves 25 minutes before 8:00 am for the other person to get moving without a muddled change of roles.

For this Snowdon alarm, silent mode deserves a check before anyone relies on the sound. Set 7:35 am, confirm the volume is audible, then use a brief test while both people are present; silent settings can prevent the alert being heard even when the time is correct. If the browser stops running or the phone falls asleep, the Snowdon sunrise handover will receive no alarm, so the person taking over should also use a separate alarm they know will ring.

Once the new person steps outside at this early hour, damp air can make exposed clothing and packed equipment feel clammy. Keep a dry layer near the top of the rucksack, protect the phone from moisture, and wipe condensation from the screen before checking the route. At 7:35 am, a small pause for those practical checks is easier than sorting wet gear higher on the mountain.

Common questions

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.

Can I use this on a phone?

It works in a mobile browser, but phones lock the screen and suspend background tabs far more readily than a laptop does, which can stop the alarm sounding. For anything important, a desktop or a plugged-in laptop is the steadier option.

Does the alarm still work if I close the tab?

No. Everything runs inside this page, so closing the tab — or quitting the browser altogether — ends the countdown there and then. Leaving it open in the background is all it asks, and switching to another tab makes no difference.