Age Calculator
Calculate exact age, age in total units and the next birthday from any date.
Enter a date of birth to calculate an exact age.
The As of date defaults to today and can be changed.
About the Age Calculator
The Age Calculator finds a person's exact calendar age from their date of birth to today or any selected As of date.
The main result breaks age into completed years, months and days. Alternative age information shows completed months, weeks, total elapsed days and hours without requiring a separate calculator.
Calendar arithmetic accounts for leap years and different month lengths. A February 29 birthday is treated as February 28 in non-leap years, a common month-end convention that keeps annual and monthly calculations consistent.
The next birthday panel shows the upcoming date, days remaining and the age the person will turn. Every calculation runs locally in the browser.
Key features
- Exact age in years, months and days
- Total months, weeks, days and hours
- Next birthday date and countdown
- Leap-year and February 29 handling
How to use
- 1Enter the person's date of birth.
- 2Keep today's date or choose another As of date.
- 3Review the exact age, alternative totals and next birthday information.
Frequently asked questions
- How does the calculator find exact age?
- It counts completed calendar months from the birth date, converts those into years and months, then counts the remaining calendar days.
- How are February 29 birthdays handled?
- In a leap year the birthday remains February 29. In a non-leap year this calculator uses February 28 as the month-end anniversary.
- Why can total days differ from years multiplied by 365?
- Calendar years vary because leap years contain 366 days. Total days counts the actual elapsed calendar days between the two dates.
- Can I calculate age on a past or future date?
- Yes. Change the As of date to any date on or after the date of birth. A date before the birth date is rejected.
- Are the total hours affected by daylight saving time?
- No. These are date-only values, so total hours uses exactly 24 hours for each elapsed calendar day rather than local clock changes.