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Age Calculator

This age calculator turns your date of birth into your exact age in years, months and days. It also counts the total days, weeks and months you have lived, names the weekday you were born on, and counts down to your next birthday. Every result updates live as you type a date.

Built & reviewed by the TurboTeamTools team · Updated September 2026 · 0 uses on this device

Age Calculator tool

Your age
–
–Total months
–Total weeks
–Total days
–Born on a
–Next birthday in

How to use it

  1. Pick your date of birth.
  2. Leave the second date as today, or set it to any date to find your age then.
  3. Read your exact age and the extra stats below.

What is chronological age?

Chronological age is the time that has passed since your date of birth, counted in full calendar units. The calculation subtracts one date from the other, one unit at a time:

age = target date - birth date (years first, then months, then days)

Years come off first, then months, then days. When the day of the month goes negative, the calculator borrows the length of the previous month, which is how it copes with months of 28 to 31 days. Someone born March 15, 1990 turns exactly 36 on March 15, 2026, and every calendar day in between, leap days included, feeds the running totals of days, weeks and months.

Worked example

Input: Born 03/15/1990, today
→
Result: Age in years, months and days, plus days lived

US age milestones and days lived

AgeDays lived (approx.)Milestone
165,844Can get a driver's license in most states
186,574Voting age and legal adulthood
217,670Minimum drinking age
6222,646Earliest age for Social Security retirement benefits
6523,741Medicare eligibility
6724,472Full Social Security retirement age for anyone born in 1960 or later

Day counts use the 365.25-day average year, so your exact total can differ by a day or two.

How age is counted

Your age in years, months and days comes from comparing your birth date with the target date, one unit at a time. Someone born March 15, 1990 is, on January 10, 2024, exactly 33 years, 9 months and 26 days old: 33 full years to March 15, 2023, nine full months to December 15, and 26 days from there. When the target day of the month is earlier than your birth day, the calculator borrows a month and adds the length of the previous month, which is why the day count can differ from a simple subtraction. Months are different lengths, and the math has to respect that.

The total days figure counts every day between the two dates, leap days included, so the same person has lived 12,354 days on that January morning. A year averages 365.25 days, which means your 10,000th day arrives at about 27 years and four and a half months, and your 20,000th at roughly 54 years and 9 months. Weeks are the total days divided by seven, and total months are years times twelve plus the leftover months.

Birthdays, leap days and other dates

The next-birthday countdown finds your birthday in the current year and, if it has already passed, jumps to next year's. If you were born on February 29, the tool places your birthday on March 1 in years without a leap day, which is also how many government agencies treat it for legal purposes. The ‘Born on a’ box uses the standard calendar, so it can tell you that January 1, 2000 was a Saturday.

Set the ‘Age at date’ field to any other date to answer a different question: how old you were when you started school, how old a parent was on the day you were born, or how old you will be in a future retirement year. The same subtraction works for anything with a start date, so people use it for work anniversaries, pet ages and how long a lease or warranty has been running.

Common uses

  • Finding your exact age for forms
  • Counting down to the next birthday
  • Working out age on a specific date
  • Checking age gaps and milestones
  • Finding how many days old you are
  • Checking the weekday you were born on

When to use it

  • You need your exact age in years, months and days for a visa, insurance or school form.
  • You are curious how many days old am I today, or when your 10,000th day falls.
  • You want to know how old you will be in 2040 without counting on your fingers.
  • You are settling the exact age difference between two people down to the day.
  • Retirement planning has you counting the years until 62, 65 and 67.

Related tools

The BMI Calculator covers the other personal number health forms ask for.

The Roman Numeral Converter writes a birth year like 1990 as MCMXC for an engraving or tattoo.

The Printable Calendar 2027 helps you mark the next birthday once you know the date.

Frequently asked questions

Enter your date of birth and the tool compares it with today, giving your age in years, months and days along with the total days you have lived. By hand, subtract the years first, then the months, then the days, borrowing a month when the day count goes negative.
Enter your birth date and read the ‘Total days’ box. It counts every calendar day from your birth date up to today, including leap days. As a rough check, multiply your age in years by 365.25: a 40-year-old has lived about 14,610 days.
Yes. The total days figure includes every leap day between your birth date and the target date. Someone born in 1990 has lived through nine of them by 2026 (1992 through 2024), which is why days lived is not simply years times 365.
Your years, months and days are calculated normally. For the birthday countdown, the tool uses March 1 in years that have no February 29, so in a leap year your next birthday falls on the 29th and in other years on March 1.
Yes. Change the ‘Age at date’ field to any date to see how old you were or will be then. It works for questions like how old you will be in 2040, or how old you were on the day you graduated.
Enter the older person's birth date as the date of birth and the younger person's birth date in the ‘Age at date’ field. The result is the exact gap between them in years, months and days, which stays the same for life.
Almost everywhere it is the international method used here: you turn one on your first birthday. Some East Asian systems traditionally counted a newborn as one and added a year each New Year. South Korea officially switched to the international method in 2023.
Dates are entered with your device's date picker and displayed in US MM/DD/YYYY style. The picker handles the month and day order for you, so there is no risk of mixing up 03/05 and 05/03 the way a typed date can.