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Birthday Countdown

See how many days are left until a birthday and which day of the week it falls on. Enter just the month and day.

What this tool does

See how many days are left until a birthday and which day of the week it falls on. Enter just the month and day. You fill in these fields: Count from, Month (1 to 12), and Day of the month. Some fields appear only for certain choices. It shows days to go, date, and weeks and days.

Inputs

  • Count from: A date. Starts as today's date. Defaults to today. Change it to count from another day.
  • Month (1 to 12): A whole number. Accepts 1 to 12.
  • Day of the month: A whole number. Accepts 1 to 31.
  • In a year without a February 29, use: Choose one: February 28, March 1. Starts as February 28. Shown only for some combinations of the other fields.

How to use

  1. Pick a date for "Count from".
  2. Enter the month (1 to 12).
  3. Enter the day of the month.
  4. When this field is shown, choose February 28 or March 1 for "In a year without a February 29, use".
  5. Read the result: days to go, date, and weeks and days. It appears once every required field has a valid value.

Worked examples

Example 1. Inputs:

  • Count from: October 8, 2026
  • Month (1 to 12): 2
  • Day of the month: 29
  • In a year without a February 29, use: February 28

Results:

  • Days to go: 143 days
  • Date: Sunday, February 28, 2027
  • Weeks and days: 20 weeks, 3 days

How this is worked out: 2027 is not a leap year, so the rule moves it to Feb 28. Oct 8 to Feb 8 = 31 + 30 + 31 + 31 = 123, plus 20 = 143.

Example 2. Inputs:

  • Count from: October 8, 2027
  • Month (1 to 12): 2
  • Day of the month: 29
  • In a year without a February 29, use: March 1

Results:

  • Days to go: 144 days
  • Date: Tuesday, February 29, 2028
  • Weeks and days: 20 weeks, 4 days

How this is worked out: Reviewer vector. 2028 is a leap year, so the birthday falls on the real February 29 and the March 1 choice is not used. Oct 8 to Feb 8 = 31 + 30 + 31 + 31 = 123, plus 21 = 144. 2027-10-08 is a Friday (one year, 365 days, after Thursday 2026-10-08); 144 mod 7 = 4, and Friday plus 4 is Tuesday.

Example 3. Inputs:

  • Count from: April 1, 2026
  • Month (1 to 12): 4
  • Day of the month: 1

Results:

  • Days to go: 0 days
  • Date: Wednesday, April 1, 2026
  • Weeks and days: 0 weeks, 0 days
  • Note: That day is the day you picked, so there are 0 days to go.

How this is worked out: The start date is itself April 1, so the count is 0 and the date is the same day.

Example 4. Inputs:

  • Count from: March 31, 2026
  • Month (1 to 12): 4
  • Day of the month: 1

Results:

  • Days to go: 1 day
  • Date: Wednesday, April 1, 2026
  • Weeks and days: 0 weeks, 1 day

Where this comes from

The next time a month and day comes round. Finds the next time a month and day comes round, on or after the start date. If the start date is that day, there are 0 days to go. A February 29 date is observed on February 28 in a year that is not a leap year. Source: The Gregorian calendar: month lengths and the leap year rule (every fourth year, except century years not divisible by 400).

Limitations

  • Counts to that day only, each year. An event held on a nearby weekday or weekend instead is not accounted for.
  • Counts whole calendar days and ignores time zones and the time of day.
  • Uses the Gregorian calendar for every date, for years 1 to 9999.

FAQs

Q: What does it count down to?
A: That day, the next time it comes round on or after the date you count from.
Q: What if the date I count from is that day?
A: The tool shows 0 days and says so. It does not skip ahead to next year.
Q: What if that day has already passed this year?
A: It counts to that day of the following year.
Q: Can I count from a date other than today?
A: Yes. Change the Count from date. It starts as today's date.
Q: Does the count include the day I start from?
A: No. It counts the days between the two dates, so the day before that day shows 1 day.
Q: How are the days counted?
A: As whole calendar days from the start date to the target date, with leap years included. Time of day and time zones are ignored.
Q: What happens to a February 29 date in a year without one?
A: You choose whether it is kept on February 28 or on March 1. February 28 is used unless you choose March 1.

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