🔍 Date of Birth (DOB) Finder
Know exactly how old someone is (in years, months, and days) but not their actual birth date? This tool runs the age calculation in reverse — enter the age, and get the calendar date it corresponds to.
How the Date of Birth (DOB) Finder works
It subtracts the years, months, and days you enter from the reference date (today, by default), correctly handling month-length differences and leap years along the way.
Step-by-step calculation
- 1Enter the age in years, months and days.
- 2Choose the reference date (today by default).
- 3The years, months and days are subtracted from it.
- 4Read the matching date of birth.
Worked example
A person who is 30 years, 2 months and 5 days old on November 14, 2026 was born on September 9, 1996.
Date of Birth (DOB) Finder examples
| Years | Estimated date of birth |
|---|---|
| 18 | January 1, 2008 |
| 25 | January 1, 2001 |
| 30 | January 1, 1996 |
| 45 | January 1, 1981 |
| 65 | January 1, 1961 |
Reference date: January 1, 2026 (0 months, 0 days). Other inputs kept at the calculator's default values. Results calculated by this calculator.
Why use a Date of Birth (DOB) Finder?
Work backward from a known age to a birth date — useful for records, research and puzzles.
Important factors that can affect your results
- If you only know the age in years, the exact birth date can be anywhere in a 12-month window.
- Month-end dates (like the 31st).
- The reference date you choose.
Frequently asked questions
What if I only know the age in years?
Just leave the months and days fields at 0 — the calculator will still work.
Can I find a birth date as of a date other than today?
Yes, use the "As of date" field to set any reference date.
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Last reviewed November 2026 · How we build and check our tools · Report a problem