A meeting booked for just after lunch is the one most likely to catch someone out, because the morning overruns and nothing interrupts the drift. This page counts down to 1:20 pm exactly, updating continuously, which is more reliable than a mental note to check back in a bit.
The figure on this page comes from your own device's clock, checked continuously and recalculated every second against 1:20 pm. There is nothing to press and nothing to set up first — the count is already running by the time the page has finished loading, and it keeps going while you are looking at it.
Matching what somebody said against what somebody wrote is easier with all three versions to hand: 1:20 pm for everyday reading, 13:20 for anything printed in railway style, and twenty past one in the afternoon for whatever was actually spoken down the phone. All three describe precisely the same point in the day, and having them side by side saves a good deal of squinting at a timetable.
Common questions
Does the number update by itself?
Yes. It recalculates every second from your device's clock, so there is nothing to refresh or restart. Whatever is on screen is the current gap to the target time, not a figure worked out when the page first loaded.
What happens if 1:20 pm has already gone for today?
The count simply carries on towards the next occurrence, which is tomorrow. That rollover happens on its own — the page does not need reloading and there is nothing to reset by hand.
Which clock does it use?
Your own. It reads the local time and time zone from the device you are looking at, so the figure reflects where you actually are rather than a fixed zone written into the page.
Will this alert me when the time arrives?
No. It is a live number rather than an alarm — nothing rings, buzzes or notifies you at zero. If you need to be interrupted at 1:20 pm, set an alarm as well and treat this page as the running total.