calculator
Age Calculator
Use the age calculator to find completed years, months, and days from a birth date to today or any selected date.
Calculate exact calendar age from a birth date to today, a birthday, an application date, a school form date, or another comparison date.
Result
Read the calendar result correctly
Enter a birth date and as-of date to calculate completed years, months, and days. For a February 29 birth date, this calculator uses March 1 in a non-leap year; an official rule may instead use February 28 or another convention, so confirm the official cutoff or eligibility rule before relying on the result.
How it works
Check the birth date
Enter the calendar date shown on the source record. The calculator uses date-only values, so it does not infer a birth time, timezone, or timestamp.
Choose the as-of date
Leave the comparison blank to use today's local date, or enter the exact application deadline, birthday, school cutoff, or form date you need to check.
Read completed calendar units
Interpret completed years first, then completed months, then the remaining days. Do not round the result up to the next birthday or combine the units as decimal years.
Verify the official rule
Before submitting a form or making an eligibility decision, confirm the required cutoff date, completed-age rule, and leap-day convention with the responsible organization.
Examples
Same-day birthday
Input: 2000-08-15 to 2026-08-15
Output: 26 years, 0 months, 0 days
Before birthday
Input: 2000-12-01 to 2026-08-15
Output: 25 years, 8 months, 14 days
Infant age
Input: 2026-01-20 to 2026-08-15
Output: 0 years, 6 months, 26 days
Eligibility cutoff
Input: 1995-04-10 to 2026-08-15 application deadline
Output: 31 years, 4 months, 5 days
Leap-day birthday
Input: 2000-02-29 to 2026-03-01
Output: 26 years, 0 months, 0 days
Insurance form
Input: 1988-11-30 to 2026-08-25
Output: 37 years, 8 months, 26 days for form review
Birthday countdown check
Input: 2010-09-02 to 2026-08-16
Output: 15 years, 11 months, 14 days
FAQ
Does this use timestamps?
No. Dates are interpreted as calendar dates.
What happens for future birth dates?
The tool returns a validation error.
How are leap-day birthdays handled?
February 29 birthdays use March 1 in non-leap years in this calculator. Some official rules may use Feb 28 or another local convention.
What if I leave the as-of date empty?
The calculator uses today's local calendar date as the comparison date.
Why does the result include months and days?
Completed years alone can hide the remaining calendar difference, so the tool shows years first, then completed months, then remaining days.
Can I use this for legal age rules?
Use this as a calendar helper only. Legal, school, medical, or eligibility rules can define age differently by location.
Can I use this on an official form?
Use it to check the calendar math, then verify the exact rule, cutoff date, and required rounding convention from the official form instructions.
Does the result depend on my timezone?
The tool uses date-only values for normal calendar checks. It does not calculate from exact birth time, timezone, or timestamp data.
Can I calculate age for a past reference date?
Yes. Choose an as-of date in the past to see the completed calendar age on that specific date.
What should I check before submitting?
Check the birth date, as-of date, application deadline, local eligibility rule, leap-day convention, and whether the form asks for completed years only or years, months, and days.