Date of Birth Calculator — Age & Life Stats
Enter your date of birth to instantly see your exact age, the total number of days and weeks you have lived, and how many days remain until your next birthday.
36 yrs 0 mo 28 d
How does this calculator work?
Enter birth year, month and day; the calculator subtracts from today to give exact age in years/months/days, total days and weeks lived, and a countdown to the next birthday. All results are based on the local calendar date in the browser.
Formula
How this is calculated
The calculator subtracts your date of birth from today's date step by step. First it counts the full calendar years. Then it counts the remaining months, adjusting for the fact that different months have different lengths. The leftover calendar days complete the breakdown. "Total days lived" is simply the millisecond difference divided by 86 400 000 (one day in milliseconds), truncated to a whole number.
The "days to next birthday" figure finds your birth month and day in the current calendar year. If that date has already passed today, it moves to the same month-day next year. The progress bar shows how far through your current year of life you are — from your most recent birthday to the upcoming one.
All calculations use the local calendar date based on your browser's clock and do not account for time zones. "Today" is treated as the current calendar date, not a specific moment in time, so results are the same regardless of the hour you check them.
Frequently asked questions
Subtract the birth year from the current year for full years, then count remaining months (adjusting if the day has not yet passed this month), then count leftover days. This calculator does the arithmetic automatically and handles month-length differences and leap years.
The calculator converts both dates to milliseconds since the Unix epoch, subtracts, then divides by 86 400 000 (milliseconds per day). A person born on 1 January 1990 passes 13 000 days around mid-September 2025.
The day of the week is derived from JavaScript's Date object, which applies the proleptic Gregorian calendar. For dates before 1970 the result is mathematically extrapolated and is accurate for any date in the Gregorian calendar era.
Also known as
TG we-Calculate Editorial Team. (2026). Date of Birth Calculator — Age & Life Stats [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/date-of-birth-calculator
TG we-Calculate Editorial Team. "Date of Birth Calculator — Age & Life Stats." TG we-Calculate. 2026. https://we-calculate.com/calculator/date-of-birth-calculator.
TG we-Calculate Editorial Team, "Date of Birth Calculator — Age & Life Stats," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/date-of-birth-calculator
@misc{wecalculate_date_of_birth_calculator, title = {Date of Birth Calculator — Age & Life Stats}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/date-of-birth-calculator}}, year = {2026}, note = {TG we-Calculate} }
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