Age Calculator

Age Calculator — Quick Reference

The Age Calculator is an online tool that calculate your exact age in years, months, and days from your date of birth — plus total days lived, next birthday countdown, live seconds counter, and life milestones. Everything for the Age Calculator is on this page: the interactive calculator, the formula, a worked example, step-by-step guidance, and frequently asked questions — no other pages required.

At a glance

Main inputs

• Date of birth
• Optional birth time
• As-of date (today or custom)

Main outputs

• Exact age in years, months, and days
• Total days, weeks, hours, minutes, and seconds lived
• Next birthday countdown and turning age
• Life milestones and Journey of Life stats

Direct answers

Formula Used

The equation below is what this calculator applies. Variable definitions follow when symbols are used.

How to Calculate Your Age

The standard way to calculate age is to subtract your birth date from a reference date using calendar rules — not by dividing total days by 365.25. Months have different lengths, and leap years add an extra day, so a proper age calculator borrows days from earlier months when the day-of-month has not yet occurred.

Step one: enter your date of birth. Step two: choose an as-of date (today by default). The tool returns years, months, and days — the same breakdown most government forms mean when they ask for “age as on” a specific date.

For second-level precision, add your birth time. The live counter then ticks through hours, minutes, and seconds you have been alive — useful for curiosity, ceremonies, and teaching how time accumulates.

Age Calculator by Date of Birth

A date-of-birth calculator — sometimes called a DOB calculator or birth-date calculator — answers one question: how much calendar time has passed since you were born? Unlike guessing from your birth year alone, entering the full DOB gives exact results.

This matters when a deadline falls between birthdays. If a school requires a child to be five by 1 September, knowing only the birth year is not enough — you need the month and day. The same applies to senior discounts, sports age brackets, and work anniversaries.

Our DOB-to-age calculator runs entirely in your browser. Results sync to the URL so you can bookmark or send a link without creating an account.

Exact Age in Years, Months and Days

An exact age calculator expresses your chronological age as a full breakdown — for example, 28 years, 3 months, and 14 days — instead of rounding to “28” or writing a decimal like 28.3 years. That precision is what insurers, schools, and sports leagues expect on official paperwork.

Total days lived is shown separately: every calendar day from birth through the as-of date, including 29 February on leap years. Weeks are derived from total days; they are handy for pregnancy-style counting and early childhood milestones.

If you were born on 29 February, non-leap years use 28 February as the anniversary — a common convention this calculator follows so your age stays consistent year to year.

Birthday Calculator

A birthday calculator tells you how many days until your next birthday and what age you will turn. It must know whether this year’s birthday has already passed relative to the as-of date — otherwise the countdown would be off by a full year.

Use it to plan parties, passport renewals, milestone trips, or retirement dates tied to a specific birthday. The turning age (“you will be 40”) is different from the age you are currently living in during the months before that birthday.

When today is your birthday, the countdown shows zero days and celebrates the exact year boundary — every year, month, and day counter resets in sync.

Age in Weeks, Days, Hours, Minutes and Seconds

Beyond the year-month-day breakdown, many people want age in days (“how many days old am I?”), age in weeks for infant development, or age in hours and minutes for novelty and education.

Without birth time, the calculator assumes midnight at the start of your birth date. Add birth time to unlock a live seconds counter that updates every second — the closest an online tool can get to “how old am I right now?” without installing software.

Journey of Life stats translate your span into weeks lived, estimated heartbeats, and breaths — a human-readable way to grasp long time periods without staring at eight-digit day counts.

Age Difference Between Two People

To find the age gap between two people, enter the older person’s date of birth as the birth date and the younger person’s date of birth as the as-of date. The result is the exact calendar span between them in years, months, and days.

Example: born 10 March 1985 (birth date) and 22 July 1992 (as-of date) gives a difference of 7 years, 4 months, and 12 days. Swap the dates to measure the gap the other direction.

This works for siblings, couples, historical figures, or any two milestones. For retirement planning from your own age, pair this tool with our retirement calculator once you know how many years remain until your target age.

• Retirement Calculator — years until your target retirement age
• Age by date of birth guide — school age, corrected age, and more
• BMI Calculator — healthy weight range for your height and age

Step-by-step

1. Enter your date of birth in the Age Calculator above. Add birth time if you want a live seconds counter.
2. Leave “as of” on today for your current age, or pick any date for historical or future age checks.
3. Read exact years, months, and days plus total days lived and your next birthday countdown.
4. To compare two birth dates, enter the older DOB as birth date and the younger DOB as the as-of date.

Age — Frequently Asked Questions

Each question is answered directly below. Expand any item for the full response.