Date & Time calculator
Birthday Calculator
Find your next birthday, day of week born, and age details.
About the birthday calculator
The birthday calculator tells you when your next birthday is, what day of the week you were born, and how many days until your next celebration.
How to use this calculator
- 1
Enter birth date
Select your date of birth.
- 2
View results
See your next birthday date, day of week, days until, and total days lived.
How the calculation works
Calculates the next occurrence of the birth date, the day of week it falls on, and the age you will be.
Example: Born on Mar 15, 1990: next birthday is on a Saturday, turning 35.
How date calculations work
Calendar math is trickier than it seems. Months have 28–31 days, leap years add an extra day every four years (except century years not divisible by 400), and time zones complicate exact hour counts. Our calculators use UTC-based date arithmetic to ensure consistent results regardless of your local time zone.
Important limitations
This tool provides a mathematical estimate based only on the values entered. It does not account for regulations, taxes, lender fees, market conditions, or individual circumstances. Results are for planning purposes only — consult a qualified professional for regulated, medical, financial, or construction decisions.
Frequently asked questions about birthday calculator
How accurate is the birthday calculator?+
The calculation follows the displayed formula and retains full numeric precision before formatting the result.
Can I use the result professionally?+
Use it as a planning estimate. Confirm regulated, medical, financial, or construction decisions with a qualified professional.