Birthdays are the dates people count down to most. This birthday calculator tells you how many days are left until your next one, which day of the week you were born, when your half-birthday falls, and the weekday of each of your next twelve birthdays, so you can see which ones land on a weekend.
How to use the birthday calculator
- Enter your birthday (your date of birth, including the year).
- Leave Count from set to today, or choose another date to count from.
- If you were born on February 29, choose February 28 or March 1 for years without a leap day.
The tape shows the countdown, the weekday you were born, the weekday and age of your next birthday, your next half-birthday and the number of days you have been alive. The table below lists your upcoming birthdays.
How the countdown is calculated
The next birthday is the first anniversary of your birth date that falls on or after the count-from date:
Both dates are whole calendar days, so the count does not change when clocks move for daylight saving time. A half-birthday is found the same way, using the dates six months after each birthday.
Worked example
Born March 15, 1995, counting from October 11, 2026:
- March 15, 1995 was a Wednesday, the 74th day of 1995.
- The next birthday is Monday, March 15, 2027, your 32nd.
- From October 11, 2026 to March 15, 2027 is 155 days (5 months and 4 days).
- The next half-birthday is September 15, 2027; the one in 2026 has already passed.
- You have been alive 11,533 days.
The upcoming-birthdays table shows the weekday sliding forward: Monday in 2027, then Wednesday in 2028 (a two-day jump because February 29, 2028 comes before March 15), Thursday in 2029 and Friday in 2030.
Weekday patterns
| Gap since last birthday contained Feb 29? | Weekday shift |
|---|---|
| No | +1 day (Monday → Tuesday) |
| Yes | +2 days (Monday → Wednesday) |
Because of this uneven step, a birthday returns to the same weekday after 6, 11 or 5 years in a repeating pattern, and the whole sequence repeats every 28 years as long as no century year without a leap day (like 2100) gets in the way.
February 29 birthdays
About one person in 1,461 is born on a leap day. They celebrate on February 29 in leap years such as 2028 and 2032, and choose a stand-in date the rest of the time. February 28 keeps the party in February; March 1 marks the moment a full year has passed. The calculator supports both, and the age checker explains why the choice can matter for legal ages.
Make it a live countdown
For a ticking clock down to the second, with your own event name and a link you can send to friends, use the countdown timer. To see your exact age in years, months and days, use the age calculator.
Frequently asked questions
What day of the week was I born?
Enter your date of birth and the first line under the countdown shows it. For example, March 15, 1995 was a Wednesday. The day of the week calculator shows the Doomsday or Zeller arithmetic behind it.
How is a half-birthday calculated?
It is six calendar months after your birthday: March 15 gives September 15. If that month is shorter, the date moves to its last day, so August 31 gives February 28, or February 29 in a leap year.
Why does my birthday move to a different weekday each year?
A common year is 52 weeks and 1 day long, so a birthday usually shifts one weekday later. When a February 29 comes between two birthdays, it shifts two weekdays.
How often does my birthday fall on the same weekday I was born?
Gaps between matches are 5, 6 or 11 years, and the pattern repeats every 28 years within a century. A March 15 birthday that fell on a Wednesday in 1995 does so again in 2000, 2006, 2017, 2023, 2028 and 2034.