How the age calculator works
The calculator compares your date of birth with the selected target date. It first calculates the year difference, then adjusts the months and days when the target date occurs before your birthday in the same year.
Age calculation example
If someone was born on January 1, 1990, they are exactly 36 years old on January 1, 2026. If the target date is later in the year, the additional months and days are shown separately.
Months do not all contain the same number of days, so exact age is best shown as years, months and days rather than converting everything into a fixed number of days.
What is chronological age?
Chronological age is the amount of time that has passed since a person's date of birth. It is usually expressed in completed years, but exact-age calculations can also include months and days.
Frequently asked questions
How do I calculate my exact age?
Enter your date of birth and the date on which you want your age calculated. The result shows completed years plus remaining months and days.
Can I calculate age on a future or past date?
Yes. Change the target date to calculate how old you were on a past date or how old you will be on a future date.
Why does the number of days vary between months?
Calendar months contain different numbers of days, and leap years can also add an extra day in February.
Does the calculator include the birth date as a full day?
The calculation measures elapsed calendar time between the two selected dates.
Using this calculator effectively
The age calculator works from calendar dates rather than using a simple day-count approximation. That makes it useful when you need age expressed in years, months and days instead of only an estimated number of years.
Common uses
- Checking an exact age on a particular date.
- Working out time remaining until a birthday or milestone.
- Comparing ages where months and days matter as well as years.
Tips for a better estimate
- Enter the date of birth exactly as shown on the source record you are using.
- Use the intended reference date if you are calculating age for a past or future event.
- Remember that official age rules for legal or administrative purposes can depend on local requirements.
Helpful guides
How to Calculate Age · How to Calculate the Difference Between Two Dates
Related calculations
Date Calculator · Days Between Dates Calculator · Average Calculator