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Exact completed age

Age Calculator

Completed years, months, and days from a birth date to a selected as-of date, including leap-day rules.

Your numbers

Exact age

Birth date to a selected as-of date. Calendar days, not clock time.

Completed age

36 years3 months, 7 days
Total days13,248
Next birthday2027-06-15266 days
How we got this
  1. Completed age36 years, 3 months, 7 days
  2. Total days13,248
  3. Next birthday266 daysJune 15, 2027
What we assumed
  • Dates are calendar dates in UTC. Local timezone cannot shift the selected day.
  • A February 29 birthday is observed on February 28 in a non-leap year.
  • Completed years, months, and days are measured from the last observed birthday.
Technical details

Method age-v1.0.0Data Manual inputs / fixed rules

Discrepancy in the numbers? You can click Report incorrect result below or email hello@costanswer.com with the Method and Data lines.

Guide

Completed years, months, and days

CostAnswer editorialIndependent calculator publisher

Age is the completed time from a birth date to an as-of date, including leap-day rules. It is not a school cutoff, not a Medicare eligibility determination, and not a sports-league age group.

Leap days

People born on February 29 have a defined completion rule in this engine so the result stays a real calendar age. Institutions sometimes use a different convention; theirs wins for their program.

Questions about this calculator

How old am I in years, months, and days?

Enter birth date and as-of date. The page prints completed units, not a rounded “about 34.”

Does this work for a February 29 birthday?

Yes. Leap-day birthdays use this engine’s completion rule so the age stays on a real calendar. Some programs use a different convention.

Terms used here

Completed age
How many full years, then leftover months, then leftover days, under this engine’s leap-day rule.

Practical tips

For a form that wants age in whole years on a certain day, set as-of to that day.

Limits and caveats

Exact under the engine’s calendar rules. Not legal proof of age.

Results are for information. They are not legal, tax, medical, or financial advice. How the math is maintained · Report a wrong figure.

Engine notes

Rounding, versioning, and omissions that sit beside the guide rather than repeating it.

  • Dates, not clock times. Birth and as-of dates are stored as YYYY-MM-DD. Local timezone cannot slide the selected day.
  • Leap days. A February 29 birthday is observed on February 28 in a non-leap year for completed-year counting.
  • What this is not. This is not business-day math and not “days from today.” Those are separate tools.

Calculation receipt

What each number here is

This answer is arithmetic on what you enter. No outside dataset is involved, so nothing here can go out of date.

An age is calendar arithmetic between two dates.

Next

People working through dates and hours usually need these next.

EverydayDate offsetFind the calendar date a given number of days, weeks, months, or years before or after another date. Month ends are clamped.EverydayBusiness daysCount workdays between two dates, or add workdays to a date. Federal holidays are optional.EverydayDays from todayThe calendar date that is N days from today, or N days ago. Weekends still count; this is not business days.EverydayPer diemFederal travel per diem for a trip in the continental U.S.: the GSA lodging ceiling for every night, meals and incidentals for every day, and a check of your actual room rate against the cap. Type a city or ZIP.EverydayTime durationsAdd or subtract hours, minutes, and seconds as durations. Negative results stay signed and normalized.EverydayTime cardAdd shift start, end, and unpaid break across one or more days, including overnight shifts. Overtime law is not applied.