Days until the 21st
The 21st comes once a month, in every month of the year. The count starts from today’s date; pick another date to count from it instead.
- Days until the 21st
- 2
From October 19, 2026, there are 2 days until the 21st, Wednesday, October 21, 2026.
- Next 21st
- Wednesday, October 21, 2026
- The 21st after
- Saturday, November 21, 2026
Answer for the example date Monday, October 19, 2026. It changes to today's date when the page loads.
Days until the 21st: 2. From October 19, 2026, there are 2 days until the 21st, Wednesday, October 21, 2026.
Where is the next 21st?
How to calculate
Counts the days from today, or any date you choose, to the next 21st of a month, with its date and the 21st after it.
Example with the default inputs (Count from October 19, 2026) on the example date Monday, October 19, 2026: From October 19, 2026, there are 2 days until the 21st, Wednesday, October 21, 2026.
Method: Find the first date on or after the start date that is the 21st of its month, then count the days from the start date to it.
- On the 21st, the count is 0, and the 21st after is the 21st of the next month that has one.
- Every month has a 21st, so the next one is never more than a month away.
- The start date itself is not counted: from the day before, the count is 1.
- Dates are calendar days with no time of day, so a time zone or a daylight-saving change never adds or loses a day.
- Start dates from January 1, 1900 to December 31, 2400 work.
Worked examples
Each example is checked against the calculator on every build.
- Count from 2026-10-19 gives Next 21st 2026-10-21, Days until the 21st 2, The 21st after 2026-11-21.Source: IETF RFC 3339, section 5.7 (days in each month) and Appendix C (the leap year rule) (https://www.rfc-editor.org/rfc/rfc3339)
- Count from 2026-12-31 gives Next 21st 2027-01-21, Days until the 21st 21, The 21st after 2027-02-21.Source: IETF RFC 3339, section 5.7 (days in each month) and Appendix C (the leap year rule) (https://www.rfc-editor.org/rfc/rfc3339)
- Count from 2027-02-01 gives Next 21st 2027-02-21, Days until the 21st 20, The 21st after 2027-03-21.Source: IETF RFC 3339, section 5.7 (days in each month) and Appendix C (the leap year rule) (https://www.rfc-editor.org/rfc/rfc3339)
- Count from 2028-02-15 gives Next 21st 2028-02-21, Days until the 21st 6, The 21st after 2028-03-21.Source: IETF RFC 3339, section 5.7 (days in each month) and Appendix C (the leap year rule) (https://www.rfc-editor.org/rfc/rfc3339)
- Count from 2027-01-21 gives Next 21st 2027-01-21, Days until the 21st 0, The 21st after 2027-02-21.Source: IETF RFC 3339, section 5.7 (days in each month) and Appendix C (the leap year rule) (https://www.rfc-editor.org/rfc/rfc3339)
Other questions people ask
How many days until the 21st?
It depends on the date, so the count above starts from today as your device shows it. From the 1st of a month that has a 21st, it is 20 days away; on the 21st itself the count is 0. Change “Count from” to count from another date.
What if today is the 21st?
Then the count is 0, because the next 21st on or after today is today itself. The page also shows the 21st after it, which is 28 to 31 days later.
Which months have a 21st?
All 12. Every month has at least 28 days, so every month has a 21st.
How many times does the 21st come in a year?
12, one in every month.
What day of the week will the 21st be?
It changes from month to month. A 31-day month moves the 21st 3 days later in the week, a 30-day month 2, a 29-day February 1, and a 28-day February 0. The page shows the weekday of the next 21st in its date.
How are the days until the 21st counted?
From the start date (today, unless you change it) to the next 21st, without counting the start date, in calendar days. Weekends and holidays count like any other day.