How many days until Christmas?
This page counts the days, hours, minutes and seconds until 25 December begins in your own time zone, the usual meaning of "days until Christmas". It updates every second, needs nothing typed, and as soon as the day has passed it starts counting to next year's 25 December by itself.
Christmas Eve, Christmas Day and Advent
This page counts to the start of Christmas Day, 25 December, at midnight in your time zone. Many families celebrate on Christmas Eve, 24 December, in the evening; if that is your moment, the countdown here ends a few hours after it, so set a custom countdown to 24 December 18:00 if you want the eve instead.
Advent, the traditional run-up, begins on the fourth Sunday before Christmas (between 27 November and 3 December), while Advent calendars simply start on 1 December with 24 doors. Orthodox churches on the Julian calendar keep Christmas on 7 January; use the countdown page for that date.
Which time zone does the countdown use?
Midnight in the time zone your device reports, so a reader in Seoul and a reader in Lisbon each see the hours to their own midnight, nine hours apart. The target is written under the digits with its zone abbreviation, for example "KST (UTC+09:00)", so you can check it at a glance.
To count to Christmas somewhere else, such as a family video call at midnight in another country, make a custom countdown on the countdown page with that zone selected; its share link carries the exact moment, and anyone who opens it sees the same instant converted to their clock.
It stays exact in the background and rings at midnight
The remaining time is recomputed from the clock every time the page draws, so a background tab or a locked phone cannot make it drift; when you come back, the digits are simply right. Over long spans the day count is a true count of 24-hour periods, which is why a daylight-saving change in between can show as 84 days 23 hours rather than 85.
During the last 100 hours the alarm is pre-scheduled on the browser's audio clock and backed by a system timer and a desktop notification, so if the page is open at midnight it rings on time, even in a background tab on a computer. Choose the sound and volume under Alarm; on an iPhone keep the tab in front, because Safari pauses hidden pages.
On the day itself, and the year after
From midnight the page shows a greeting instead of the countdown, with how long ago the day began, and a small line with the days until next year's Christmas. Twenty-four hours later it switches back to counting, so a bookmark or a classroom display never needs resetting.
Planning backwards from the countdown
The day count is the handiest number for planning: parcel services publish last-posting dates about one to two weeks before Christmas for domestic mail and earlier for international, so when the display drops below 14 days, it is time to send. Bakers count back two to three days for a stollen or a fruit cake to rest.
For children, the number of "sleeps" is the day count on this page as long as you look at it in the morning; after bedtime subtract one. Full-screen mode (F) makes a good Advent display on a tablet in the hallway.
Other countdowns and time tools
The countdown page counts to any date and time you choose, in any time zone, and also counts the days since a past date. For a length of time starting now, such as 10 minutes, use the timer; the stopwatch measures how long something takes. New Year, Christmas, Halloween and Valentine's Day each have a page like this one.