Days until December 21
December 21 falls on a Monday in 2026 and a Tuesday in 2027. The count runs from today’s date on your device to the next December 21; pick another date to count from it instead.
- Days until December 21
- 82
From September 30, 2026, there are 82 days until December 21 on Monday, December 21, 2026.
- Date
- Monday, December 21, 2026
- Day of the week
- Monday
- In weeks
- 11 weeks and 5 days
Answer for the example date Wednesday, September 30, 2026. It changes to today's date when the page loads.
Days until December 21: 82. From September 30, 2026, there are 82 days until December 21 on Monday, December 21, 2026.
Where is December 21 on the calendar?
How to calculate
Counts the days from today, or any date you choose, to the next December 21, with its day of the week.
Example with the default inputs (Count from September 30, 2026) on the example date Wednesday, September 30, 2026: From September 30, 2026, there are 82 days until December 21 on Monday, December 21, 2026.
Method: Find the first December 21 on or after the start date, then count the days from the start date to it.
- December 21 comes every year, so the count is never more than 365 days.
- The start date itself is not counted: from the day before December 21, the count is 1; on December 21 itself, it is 0.
- Start dates from January 1, 1900 to December 31, 2400 work for the count to December 21, the range the date field accepts.
- Today is the date on your own device, so the count to December 21 changes at midnight where you are. Dates are whole calendar days, so a daylight-saving change never adds or loses a day.
Worked examples
Each example is checked against the calculator on every build.
- Count from 2027-12-21 gives Date 2027-12-21, Days until December 21 0.Source: U.S. Naval Observatory, Leap Years: the Gregorian leap year rule (https://aa.usno.navy.mil/faq/leap_years)
- Count from 2027-01-01 gives Date 2027-12-21, Days until December 21 354.Source: U.S. Naval Observatory, Leap Years: the Gregorian leap year rule (https://aa.usno.navy.mil/faq/leap_years)
- Count from 2027-12-22 gives Date 2028-12-21, Days until December 21 365.Source: U.S. Naval Observatory, Leap Years: the Gregorian leap year rule (https://aa.usno.navy.mil/faq/leap_years)
Other questions people ask
What day of the week is December 21?
Monday, December 21, 2026; Tuesday, December 21, 2027; Thursday, December 21, 2028. The weekday of December 21 moves on one day a year, or two when a February 29 falls between.
What day of the year is December 21?
December 21 is day 355 of a common year and day 356 of a leap year, such as 2028. Either way, 10 days of the year come after it.
What season is December 21 in?
In the Northern Hemisphere, December 21 is the first day of winter (the December solstice) in every year from 2026 to 2035; in the Southern Hemisphere, it is summer. Seasons here start on the astronomical equinoxes and solstices, dated in US Eastern Time.
Is December 21 a US federal holiday?
No. No US federal holiday falls on December 21. The next one in the calendar after December 21 is Christmas Day, which falls on December 25.
How are the days until December 21 counted?
From the start date to December 21, without counting the start date: from December 20 the count is 1, and on December 21 it is 0. The day after, it moves on to the next December 21: from December 22, 2026, that is December 21, 2027, 364 days away.