Time remaining
The countdown reached zero. Run it again for the same length, or set a new timer.
Up to 999 days 23:59. Minutes over 59 roll into hours, hours over 23 roll into days.
Fourteen digits: year, month, day, hour, minute, second. Any separators you type are ignored. The time is read in the zone chosen beside it, then held as a fixed instant.
The address bar already carries the end time. Bookmark this link or send it to another device to keep counting to the same moment.
Colour scheme, contrast and the accent colour are shared by every tool on this site and are set in one place. The two buttons at the top right are shortcuts for the scheme and the contrast.
Four keys in localStorage, synced across open tabs. The shared theme lives separately in dtm3. Nothing else is stored.
Starting a countdown writes the end time into the address as ?t=YYYYMMDDhhmmss-UTC. Because the moment is fixed rather than counted down in the page, closing the tab, sleeping the machine or opening the link elsewhere all land on the same finish time. A target time is converted to that same instant, so a link made in one zone reads correctly in another. Pausing removes the stamp, since a paused timer has no fixed end.