Anything due by the end of the morning brings a short burst of urgency just before the deadline lands. Knowing exactly how long is left until 11:17 am is the difference between finishing properly and rushing the last paragraph. The figure here recalculates every second, so it is never out of date.
Because the count reads straight from your device's clock, its accuracy rests on that clock being right, time zone included. Phones and computers normally handle this themselves, so in practice the figure here lines up with whatever time the device is already showing elsewhere on screen.
Plenty of phones, laptops and dashboards default to a 24-hour display regardless of how people around here actually talk, so 11:17 may well be the figure staring back at you even though 11:17 am is how the same moment would be said aloud. Neither is more correct than the other.
Common questions
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 11:17 am, set an alarm as well and treat this page as the running total.
Is it affected by the clocks changing?
Only in the sense that your device is. When the change between GMT and BST happens at the end of March and October, the device adjusts and the countdown follows it without anything to do here.
What is 11:17 in the 12-hour clock?
That is 11:17 am, or seventeen minutes past eleven in the morning if you are saying it aloud. From 13:00 onwards, subtracting twelve gives the pm figure — the same moment written three different ways.