Birthday Calculator
Find the next birthday date, days until birthday, birth weekday, upcoming birthdays and live time-lived milestones.
These are broad estimates. Actual pulse and breathing rates vary by age, activity and health; this is not a medical calculation.
Birthday countdown and date facts
This birthday calculator focuses on the birthday event: the next birthday, days remaining, the weekday you were born, upcoming birthdays and time-lived milestones.
D_next is the next observed birthday date and B(y) is the birthday placed in a given year.
Leap-day birthdays and milestones
- February 29 birthdays are observed on March 1 in non-leap years in this tool.
- Live totals update while the page is open.
- Heartbeats and breaths are broad entertainment estimates, not medical measurements.
- Use the regular age calculator when you need a formal years-months-days age breakdown.
Frequently Asked Questions
Sources and References
- DateMDN Web Docs
- Representing dates and timesMDN Web Docs
- Gregorian calendarBritannica
- Birthday Calculatortimeanddate.com
Calculations are based on the listed reference sources. Links open in a new tab.
Related Tools
Calculate exact chronological age from a date of birth to today or any as-of date, with years, months, days and total-day breakdowns.
Calculate live exact age from date and optional time of birth, with years, months, days, hours, minutes, seconds and total time lived.
Calculate how many full days you have lived from a birth date or event date, with weeks, hours, seconds and day-milestone dates.
Calculate age in full calendar months and remaining days from a date of birth to today or any target date.
Calculate the date difference between two dates or add and subtract calendar days from a start date, with full calendar breakdowns.