Date of Birth Calculator
Reverse age calculator: enter your known age in years, months, and days to calculate your estimated birth date.
Date of Birth Calculator
Determine an estimated birth date by entering your known age in years, months, and days.
Years
Months
Days
Estimated Date of Birth
January 15, 2000
Born on a Saturday
Calculated using standard calendar month borrowing. Due to varying month lengths (28–31 days), results may vary slightly depending on calendar conventions.
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When Is a Reverse DOB Calculator Useful?
A reverse date of birth calculator is invaluable in genealogy research, historical document analysis, medical intake forms, and legal record verification where only an age on a specific date is recorded rather than a complete date of birth.
Want to calculate forward from date of birth instead?Go to Age Calculator
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Helpful FAQ
Frequently Asked Questions
Find clear answers to common questions about age calculation, leap years, and date math.
The calculator performs reverse calendar subtraction by taking a reference date (such as today) and subtracting the specified number of days, months, and years while correctly borrowing calendar days from preceding months.