Birthday Calculator
Discover the day of the week you were born, calculate your exact age down to the day, and count down to your next birthday.
Birthday Calculator
Find birthday facts, exact calendar age, and your next birthday countdown.
This calculator auto-updates when values change.
Birthday facts
Wednesday
Born on Wednesday, January 7, 1970. Your zodiac sign is Capricorn, and your next birthday falls on a Thursday.
Zodiac Sign
Capricorn
Days Lived
20,571
Next Birthday
Thursday
About This Birthday Calculator
Exact age calculation is harder than subtracting years because calendars have leap years, months with different lengths, and birthdays that may not have occurred yet in the comparison year.
This birthday calculator uses calendar-aware date math to calculate years, months, days, total days lived, and next birthday details without relying on rough 365-day shortcuts.
Use it for curiosity, document age checks, birthday milestones, countdowns, or historical age calculations with a custom comparison date.
How to Use This Calculator
- 1
Find day of the week
Enter your date of birth and open Birthday Facts to see the weekday you were born.
- 2
Calculate exact age
Open Exact Age to see full calendar years, months, and days.
- 3
View total days lived
Use the breakdown cards to see total days, weeks, months, and years.
- 4
Countdown to next birthday
Open Next Birthday to see days remaining and the date you will turn your next age.
- 5
Use custom comparison date
Enter Calculate age at date to calculate age and birthday facts for a historical or future date.
Frequently Asked Questions
Does this birthday calculator handle leap years?v
Yes. Dates are calculated using calendar-aware logic, including leap years and month lengths. For February 29 birthdays in non-leap years, the calculator observes the birthday on February 28.
How are months calculated in exact age?v
The calculator counts complete calendar months after complete calendar years. It does not approximate months as 30 days.
Why does age in days not equal years times 365?v
Leap years add extra days, and calendar years vary depending on where the birthday falls. That is why total days lived can differ from a simple years x 365 estimate.
Can I calculate age on a historical date?v
Yes. Use the optional Calculate age at date input to replace today with any past or future comparison date.
What happens if my birthday is today?v
The Next Birthday tab shows 0 days and displays birthday messaging for the current comparison date.
How does timezone handling work?v
Date inputs are treated as calendar dates, not times of day. The calculator normalizes date picker values to date-only calculations to avoid timezone shifts.