The fast breaks at sunset, and sunset shifts by a minute or so each day, so the time that applied last week is not the time tonight. If 7:42 pm is this evening's figure, this page counts down to it exactly — hours, minutes and seconds — which is what everyone in the kitchen actually wants to know.
This is a display rather than an alarm. Nothing rings, buzzes or notifies at the end, and the page will not interrupt whatever else you are doing. If being interrupted is the point, set an alarm as well and treat this page as the running total you can glance at in the meantime.
Twelve o'clock is where the 12-hour clock is weakest: 12 am and 12 pm are read the wrong way round often enough to cause real trouble with bookings and deadlines. Writing the same moment as 19:42 removes the problem entirely, because a 24-hour figure only ever points at one instant in the day.
Common questions
Does the number update by itself?
Yes. It is recalculated every second from your device's clock, so nothing needs refreshing or restarting. Whatever is on screen is the current gap to 7:42 pm, not a figure worked out when the page first opened.
What happens once 7:42 pm has passed for today?
The count rolls over and carries on towards the same time tomorrow. That happens on its own at the moment the time passes — the page does not need reloading and there is nothing to reset by hand.
Which clock does the countdown use?
Your own. It reads the local time and time zone from the device in front of you, which in the Emirates means Gulf Standard Time, UTC+4. Travel and the count follows whatever the device picks up.
Will it alert me when 7:42 pm arrives?
No. This is a live figure rather than an alarm — nothing sounds, vibrates or notifies at zero. If you need interrupting at 7:42 pm, set an alarm alongside it and use this page as the running total.