Enter a known age and the date that age was recorded. The finder subtracts the duration and returns the most likely birth date based on the details you provide.
Assumes the stated age reflects every unit you entered.
Date of Birth Calculator - Find Birth Date From Age
Subtract a stated calendar age from a reference date to obtain an assumed birth date. A completed age in years alone does not identify one unique birthday; it describes a range of possible birth dates.
What the supplied age can tell you
Enter years, months and days as known, then choose the reference date. Blank age fields are treated as zero; the page needs at least one positive age value. The result updates from the supplied calendar parts.
If someone is exactly 30 years old on October 26, 2026 under that assumption, subtracting 30 years gives October 26, 1996. If you only know their completed age is 30, birthdays from October 27, 1995 through October 26, 1996 are possible. This calculator does not establish which birthday is correct.
Calendar order and month ends
The implementation subtracts days, then months, then years using the browser's local calendar setters. These operations can roll an invalid month-day combination into another month. For 1 year, 2 months and 3 days at October 26, 2026, the sequence yields August 23, 2025. Near February 29 or a month end, inspect the result rather than assuming every month is 30 days.
Check before using the assumed date
Use an original document when a verified birthday is required. An approximate age does not recover missing identity information. The arithmetic runs locally, while the site also loads analytics and advertising; avoid confidential identity or medical data.
Use the Age Calculator to compare a known birth date with a reference date. Its result remains a calculation rather than identity verification or a legal eligibility decision.