How this calculator works
The target December date is placed in the same year as the starting date. If it has already passed, the next year is used, so the answer is never negative. The day count is the number of calendar-day boundaries between the two dates, with no time zone involved. The monthly table anchors the target to the year it falls in and shows the countdown from the first of each earlier month, which is useful for planning a holiday budget or a year-end deadline.
Formula
target = 1, 25 or 31 December in the starting year, moved to the following year when it is before the starting date. days = O(target) - O(from date). Whole weeks = floor(days / 7) and leftover days = days mod 7.
Worked example
From 2026-11-01, December 1 is 30 days away, which is 4 weeks and 2 days. Christmas Day is 54 days away and New Year's Eve is 60. From 2026-12-15, the next December 1 is 2027-12-01, 351 days later.
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Frequently asked questions
Is "days until December" counted to December 1 or to the end of November?
It is counted to December 1, the first day of the month. The day immediately before is the last day of November, so the countdown from November 30 is one day. Choose Christmas or New Year's Eve in the selector for those dates instead.
Why does the count reset in December?
Once December 1 has passed, the next December 1 is in the following year, so the count jumps to around 350 days. That is the honest next-occurrence answer, and the target date line shows exactly which year it belongs to.
Does leap day change the answer?
Only when the interval crosses February 29, which happens for target years far ahead of a starting date in the previous year. The calendar arithmetic includes it automatically, so a leap year adds one to the count.
Should I count today?
The starting date is not counted as day one; the next date is. If you want an inclusive count, add one. The same convention is used by the days-until page.