Days, hours, minutes and seconds until a date that matters — Christmas by default, or any date picked below.
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The countdown counts whole calendar days first, then the remaining hours, minutes and seconds tick down live. If a preset like Christmas has already passed this year, the countdown automatically aims at next year's — so 'days until Christmas' is right in January as well as December.
How many days until Christmas? On 25 December, zero — it is today. The preset above handles the year rollover automatically and counts to the next Christmas whenever the date has passed.
Does it count the target day itself? The day count shows full days remaining before the target date arrives: with the target tomorrow, it reads 1 day (plus the hours left today).