Age Calculator
Compare a date of birth with a reference date to calculate exact age, year-count age, elapsed time, and time until the next birthday.
How to use
- Select the date of birth.
- Check or change the reference date.
- Calculate to see exact age, elapsed years/months/days, total days, and the next birthday.
Capabilities and scope
The calculator compares the birth date with a user-selected calendar date, so it can answer age questions for today as well as past or future reference dates.
How it works
It starts with reference year minus birth year and subtracts one when that year's birthday has not yet occurred. Elapsed years, months, and days follow real calendar month lengths, and date-only inputs are handled as UTC calendar dates to avoid time-zone day shifts.
Example
A birth date of January 1, 2000 is age 26 on January 1, 2026, but age 25 on December 31, 2025.
Interpretation
Exact age increases on the birthday. Use the exact-age result for ordinary official age checks.
Useful for
- Check a current exact age
- Calculate age on a contract, exam, or event date
- See the time remaining until the next birthday
Before you use it
- Legal, administrative, insurance, and medical age rules may use their own definitions; follow the relevant authority for official decisions.
- Year-count age is supplementary and is not the same as exact legal age.
Edge cases
- For February 29 births, non-leap years clamp the anniversary to the last valid day of that month.
- A reference date earlier than the date of birth is rejected.
Frequently asked questions
What is the default reference date?
The device's local calendar date is used as today, and you can replace it with another date.
How is year-count age calculated?
It is reference year minus birth year plus one and is shown only as supplementary information.