Age Calculator
Calculate exact age from a date of birth to today or another date, including years, months, days, total days, weeks, and next birthday timing.
Date of Birth
Enter a birthdate to calculate exact age.
Age
Exact age with detailed breakdown.
Age
36 years
36 yr, 6 mo, 26 days
Methodology and limitations
Last reviewed:
Methodology
Calculates exact age in years, months, and days between two calendar dates, accounting for varying month lengths and leap years.
Limitations
Uses calendar dates only; does not account for time zones.
How the Age Calculator Works
Calculate exact age from a date of birth to today or another date, including years, months, days, total days, weeks, and next birthday timing.
Method used
The calculator compares the date of birth with the selected as-of date and returns completed years, remaining months, remaining days, and total elapsed time.
Exact age = as-of date - birth date, expressed as calendar years, months, and days
Practical example
For a person born on January 1, 1990, the calculator can show age today or age on a selected past or future date.
- Date of birth: January 1, 1990
- As-of date: today or a selected date
The result shows age in years, months, and days, plus total days lived, total weeks, total months, and next birthday timing.
Assumptions
- Dates are interpreted as calendar dates.
- The as-of date defaults to the current date in the user's browser.
- Leap years and month lengths are handled through date-difference logic.
What this includes
- Exact age, total days, total weeks, total months, birth weekday, and next birthday countdown.
What this excludes
- Time of day, time zone differences at birth, legal age rules, and country-specific age definitions.
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Frequently Asked Questions
How does the age calculator count age?
It compares the birth date with the selected as-of date, then returns completed years, remaining months, and remaining days.
Can I calculate age on a past or future date?
Yes. Change the as-of date to calculate age on a specific date instead of today.
Does the calculator include leap years?
Yes. Date calculations use calendar dates, so leap years and different month lengths are handled by the date difference logic.