Age Calculator

Find your exact age in years, months, days, and more.

About Age Calculator

Enter a date of birth to calculate the exact age in years, months, days, weeks, and total hours. You can also use the optional “as of” date to find how old someone was or will be on any specific date in the past or future. The calculator also shows the date of the next birthday.

How the age is calculated

The calculator counts the exact number of calendar years, months, and days between the birth date and the target date, correctly handling leap years and months of different lengths. The total days figure is the raw day difference between the two dates, while weeks is that number divided by 7.

Common use cases

  • Verify minimum age — confirm whether a person meets the age requirement for a contract, driving licence, or consent form.
  • Find age on a past event — how old were you on a specific day? Use the “as of” date to find out.
  • Plan a milestone birthday — find exactly when someone turns 18, 21, 30, or 65 years old.
  • Employee or student records — calculate current age from a date-of-birth field for reporting.

About the Age Calculator

An age calculator returns your exact age in years, months, days — and optionally hours, minutes, and seconds — based on your date of birth and a target date (usually today). It also shows how many days remain until your next birthday and what day of the week you were born on.

Calculating age cleanly is harder than it sounds. Months have different lengths, leap years complicate February, and the difference between "complete months" and "calendar months" trips up many naïve implementations. This calculator computes the canonical "Y years, M months, D days" form used in legal and medical contexts.

How calendar age is calculated

Take the target date and subtract the birth date in a step-down fashion. First subtract years: how many full years have elapsed? Then months within the current year. Then days within the current month, borrowing from the months count if the target day is earlier in the month than the birth day. This is how passports, insurance forms, and medical records compute age. It is also the form most people intuitively expect.

Why leap-year birthdays are special

A baby born on 29 February has a birthday only every four years (with adjustments for the century rule). Legally most jurisdictions treat 1 March as the birthday in non-leap years for documents requiring "the date of birth", but local rules vary. This calculator follows the convention of using 28 February or 1 March consistently and shows the next leap 29 February as the "real" next birthday.

How to use the Age Calculator

  1. Enter date of birth

    Use the date picker or type YYYY-MM-DD directly.

  2. Optionally enter a target date

    Defaults to today. Use a future date to find someone's age on a particular occasion (a wedding, a retirement date, a school cut-off).

  3. Read the breakdown

    Years, months, days, total days lived, and time to next birthday are all shown.

Worked examples

Example 1

Input: DOB 1990-05-14, today 2026-06-06

Result: 36 years, 0 months, 23 days

Standard "years, months, days" form.

Example 2

Input: DOB 2000-02-29

Result: Next birthday: 2028-02-29 (real leap day)

Leap-day births skip three years out of four for the "real" birthday.

Real-world use cases

  • Filling forms that require age in years and months (school applications, medical history).
  • Checking eligibility for age-restricted services.
  • Counting how many days you have been alive (often a fun statistic).
  • Planning a milestone birthday celebration months in advance.
  • Computing the age someone will be on a specified future date.

Tips & common mistakes

  • For legal forms, prefer the "Y years M months D days" form — it removes ambiguity around partial years.
  • If you only need age in whole years, the field labelled "years" is what you want. Months and days are calendar-correct, not approximate.
  • Date arithmetic that ignores time zones is fine for age. The calculation uses calendar dates, not absolute instants.

Frequently asked questions

How accurate is the calculation?

Exact to the day for any pair of valid dates. The total-days count is a true count, not an approximation.

Does it handle dates before 1900?

Yes. The Gregorian calendar is used throughout; for dates before 1582 the result is a proleptic Gregorian count, which is the conventional choice for historical calculations.

What time zone does it use?

Your local time zone, taken from your browser. Age is a calendar concept, so time zone affects the calculation only around midnight.

Why is "next birthday" sometimes today?

If your birth date in the current year is today, the days-until-birthday is 0 and the next birthday is one year away.

Related tools

→ Date Difference→ Percentage Calculator

Last updated: June 2026 · All processing happens locally in your browser.