Birth date calculator

Find your exact birth date from your age plus your birthday date. It auto-adjusts if the birthday hasn’t happened yet and includes an advanced mode for past reference dates.

Enter your current age, your birthday date and, if needed, a reference date other than today. We will pinpoint your birth date and automatically validate temporal consistency.

Day
Month
We validate impossible dates, including leap-year birthdays.
Birth date
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Enter your age and birthday to estimate your birth date.

How we calculate your birth date

We subtract the age you provide from the reference date (today by default) and place your birthday on the real calendar. If the anniversary for that year has not yet happened, we shift one year back so the result stays coherent. We also validate that the birthday date exists, even for February 29 births.

Then we perform a reverse check: we recalculate the age from the obtained birth date to the reference date. If anything differs, we display an alert so you can fix the data before using the result.

Advanced mode for past dates

Switch to advanced mode and set the reference date. That way you can retrieve your real birth date from the age you had in a photo, contract, or old document. The calculation keeps the Gregorian calendar and adjusts for birthdays that have not yet happened.

What we show you

  • Estimated birth date.
  • Reference date used and last anniversary.
  • Next anniversary and countdown.
  • Recalculated age as a coherence check.
What if I have not had my birthday yet this year?

We handle it automatically. If the birthday has not arrived on the reference date, we subtract an extra year so the age matches.

Does it work for February 29 birthdays?

Yes, as long as the calculated year is a leap year. Otherwise, we will alert you to adjust the age or reference date.

Can I use it for old documents or photos?

Activate advanced mode, set the document or photo date as the reference, and enter the age you had then. You will get the same birth date.

Do you save the data I enter?

No. Everything is calculated in your browser and we do not store your dates.

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