Set the alarm clock for 7:42 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 7:40 am Alarm clock for 7:41 am Alarm clock for 7:43 am Alarm clock for 7:44 am

Going to bed for a 7:42 am alarm

Asleep by 10:27 pm — 6 full sleep cycles, about 9 hours
Asleep by 11:57 pm — 5 full sleep cycles, about 7 hours
Asleep by 1:27 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.

7:42 am across the country

London	7:42 am
Birmingham	7:42 am
Manchester	7:42 am
Glasgow	7:42 am
Belfast	7:42 am

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

How to use the online alarm clock

Finishing security at Heathrow at 7:42 am means gathering your passport, liquids bag and hand luggage before leaving the checkpoint. An alarm set for this moment marks the point to stop repacking and head towards the departure screens or gate. With 8:00 am approaching, there is still time to check the gate number without lingering among the trays.

Once you move away from security, the alarm page may sit behind the airline app or a digital boarding pass. A browser can reduce activity on a page left in the background, so the alert may arrive late or its sound may be restricted. Keeping the page open and the sound permission enabled gives it a clearer chance to run as expected. If the browser session ends or the phone goes to sleep, however, the alarm cannot sound, so it should not be the only safeguard for an early Heathrow flight.

After an early checkpoint exit, a few sips of water and a familiar, easy-to-carry breakfast are more practical than a large meal that takes time to find and finish. At 7:42 am, anything bought should fit the walk to the gate and possible queueing nearby. A longer coffee stop can wait until the gate is confirmed and the remaining time is visible.

Common questions

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.

What happens if my laptop goes to sleep before 7:42 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.