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Birthday Calculator

Created by Rita Rain
Reviewed by Dominik Czernia, PhD, Jack Bowater and Adena Benn
Last updated: Jun 05, 2023

The birthday calculator will give you an accurate answer to the question, "When is my birthday?". It can also serve as an age calculator or a date of birth calculator (in case you know exactly how many days old you are). You can also find out the dates of your past birthdays (in case you're wondering, e.g., "when was my 14th birthday?").

Fun fact - there's a 50% chance that at least two people in a group of 23 share a birthday. If you like to learn more about this visit our Birthday Paradox Calculator.

Image of a birthday cake.

Birthday calculator - When is my birthday?

If you're wondering, "When is my birthday?" you're just a few clicks away from the answer:

  1. In the first field of the birthday calculator, click the calendar icon and choose your date of birth. You can also type it in (the first three letters of the month followed by the day, and the year, e.g., "Sep 25, 1980").

  2. In the second field, you can set the date for which you want to calculate your age and the time left until your next birthday. By default it is set to today. If you want to include the time in the calculations, switch to advanced mode.

  3. Based on these two dates, the birthday calculator will estimate your age and display it in the third field. You can choose between different units of time to find out how many seconds, days, weeks, etc., you have lived.

  4. Under the birthday calculator, you'll see the time left until your next birthday.

Are you interested in learning how many months there are between two dates? Visit our intuitive month calculator.

Date of birth calculator and other ways to use the tool

Our tools enable calculations in different directions. This feature lets you answer a wider variety of questions.

Let's see what questions this birthday calculator/date of birth calculator can answer and how to go about it.

  1. When was I born?

    Well, we don't have access to any magical CIA/FBI databases, so we don't know your date of birth 🙃. You could probably ask your family or check your birth date on your ID.

    Theoretically, you could use our birthday calculator as a date of birth calculator, but you'd have to know your exact age. So, if it's your birthday, and you know you're 85 but forgot your date of birth, enter the age, and the day of birth will be determined.

  2. When was my 14th birthday?

    Let's say you're asking yourself, "When was my 14th birthday?". In this case, enter "14" in the "age" field, and your date of birth in the date of birth field, and the date of your 14th birthday will appear in the second field of the birthday calculator.

  3. When was I 10,000 days old?

    Firstly, set your date of birth in the first field. Then set the unit in the last field to "days" and enter "10,000". In the On... field, you'll see the day on which you were or will be 10,000 days old.

  4. When will I be 100 years old?

    Proceed in the same way as in point 3 but set the unit to "years" and enter "100".

  5. How long would I have to live to see the first day of the 22nd century?

    Set your birthdate in the first field. Then type in "Jan 1, 2101" in the second field. Your age will be displayed in the last field of the birthday calculator.

The ancient roots of birthday traditions

Have you ever wondered "How we developed the custom of blowing candles out on our birthdays?"

The history of celebrating birthdays is strictly connected to the invention of the calendar. Before it, there was no way to mark and conceptualize birthdates.

In the beginning, birthdays were thought to be dangerous, and we're not talking about the amount of alcohol consumed. The ancient pagan cultures believed that evil spirits visited the man on his birthday. For this reason, a community would gather to protect him and wish him well. People would dance and sing loud to scare the demons away.

Ancient Romans' birthdays were also connected with a spirit, although not a malicious one. The being was a guardian spirit called "genius." It accompanied a man throughout his life since birth and protected him. A birthday would be a ceremony to honor one's genius. Romans would sacrifice a bread cake and some wine for the spirit. On a paterfamilias (landowners') birthday, relatives also lit candles, expressed wishes, and gave blessings.

And what about the cake? We know that the ancient Greeks took a round cake with candles to the Temples of Artemis - the moon goddess. They believed that lighting candles enabled connection with gods.

Source: Redlich, O. (2020). The Concept of Birthday: A Theoretical, Historical, and Social Overview, in Judaism and Other Cultures.

Rita Rain
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