Online Calculators
Most Used CalculatorsMath CalculatorsDate and Time CalculatorsConversion CalculatorsStatistics CalculatorsFinance CalculatorsHealth CalculatorsEducation CalculatorsAll Calculators

Date and Time Calculators

Age Calculator

Use this age calculator to find age in years, months, and days between a birth date and an as-of date.

Primary answer
Age
Inputs to verify
Birth date and Age on
Use type
Use as a direct calculation check.
Keyword intent
age calculator

Calculator

Age Calculator

Calculates age from birth date, age on. Defaults are filled in so you can review a working example before changing inputs.

Use a real Gregorian calendar date.

The date on which age is calculated.

Result

Result reflects the current submitted inputs.

  • Risk A
  • Reviewed 2026-05-26
  • 1 sources
Age36 years, 0 months, 11 days
Total days13,160
Next birthday2027-05-15
  • Dates are interpreted at UTC midnight to avoid local daylight saving changes.
  • The as-of date must be on or after the birth date.

Accuracy notes

Risk level
A
Reviewed
2026-05-26
Sources
1
Primary result
Age

Formula logic is kept in a pure calculator module with fixtures, source notes, and page-visible assumptions.

Categories

What the result means

The age summary is the completed calendar age on the selected as-of date, not a decimal-year estimate. Use the total-day count when a policy, event, or record needs an exact elapsed-day interval, and use the next-birthday value only as a planning aid.

AgeDisplayed as text.
Total daysDisplayed as integer.
Next birthdayDisplayed as date.

Use the result this way

  1. Start with Age, then use supporting outputs for context.
  2. Verify Birth date and Age on before copying the result.
  3. Check the formula, example, and assumptions before reusing the answer.

User job

How to use this calculator

Use Age Calculator when you need age, then use total days and next birthday to check the context for calendar planning, work logs, schedules, eligibility checks, and duration comparisons.

Best for

  • Turning dates or clock times into a clear interval
  • Checking whether a deadline or duration is plausible
  • Reviewing a default example before entering your own birth date and age on.

Check before relying

  • Confirm calendar convention, time zone, overnight handling, and whether endpoints should be included.
  • Dates are interpreted at UTC midnight to avoid local daylight saving changes.
  • The as-of date must be on or after the birth date.
  • Source context: International Organization for Standardization, reviewed 2026-05-26.

Next useful step

  • Date CalculatorUse next when your task shifts from Age Calculator to Date Calculator.
  • Time Duration CalculatorUse next when your task shifts from Age Calculator to Time Duration Calculator.
  • Hours CalculatorUse next when your task shifts from Age Calculator to Hours Calculator.

Formula

Completed years, months, and days are counted by comparing the birth date with the as-of date on the Gregorian calendar.

  • Completed years, months, and days are counted by comparing the birth date with the as-of date on the Gregorian calendar.
  • Enter the birth date and the date on which you want to know the age. The as-of date must be on or after the birth date.
  • Last reviewed: 2026-05-26.

Inputs

Enter the birth date and the date on which you want to know the age. The as-of date must be on or after the birth date.

Birth dateUse a real Gregorian calendar date.
Age onThe date on which age is calculated.

Example

A birth date of 1990-05-15 and an as-of date of 2026-05-26 gives 36 years, 0 months, and 11 days.

FAQ

How is age calculated?

The calculator counts completed calendar years first, then remaining months and days between the birth date and as-of date.

Does this account for leap years?

Yes. It uses real Gregorian calendar dates and validates that each entered date exists.

Can I calculate age on a future date?

Yes. Enter the future date as the as-of date to calculate age on that day, including total days and next birthday context.

Why does total days differ from years times 365?

Calendar years include leap years and months with different lengths, so total days should be counted directly.

What should I verify before using age calculator?

Verify birth date and age on, the displayed formula, and the worked example before copying the result into another document or decision.

What is the main output of age calculator?

Age is the first value to read. Use the supporting outputs and assumptions to understand why it changed.

Sources

Last reviewed: 2026-05-26

  • Reviewed 2026-05-26
    ISO 8601 date formatInternational Organization for Standardization. Date input follows the YYYY-MM-DD convention.