Countdown to a date and time

How the countdown stays accurate

The date and time you enter are read as a wall-clock time in the chosen zone, then converted to one exact moment using the time zone database built into your browser. That database knows when each place switches to or from daylight saving time, so a countdown that crosses a clock change is still exact, even if your own zone changes on a different day.

If you pick a time that happens twice because clocks fall back, the first occurrence is used. If you pick a time that is skipped when clocks spring forward, the countdown uses the moment the clocks jump past it, and a note says so.

The countdown follows your device clock. If that clock is wrong, the countdown will be off by the same amount.