Age Calculator

Whether you’re filling out a form, settling a debate, or simply curious about the answer to “how old am I today?”, our age calculator gives you an instant, precise answer. Enter your date of birth, optionally add your time of birth, and see your exact age broken down however you like in years, months, weeks, days, hours, minutes, seconds, or even milliseconds.

What Is My Age?

Your age is simply the amount of time that has elapsed since you were born. In most countries around the world, a newborn begins life at age zero and turns one year old on the first anniversary of their birth. This is the standard system used across Europe, the Americas, Africa, and most of Asia.

Some East Asian countries historically used a different counting method where a person is considered one year old at birth and gains a year each lunar new year. South Korea officially moved away from this system in June 2023, adopting the international standard. Our age calculator uses the international standard throughout.

While we typically express age in whole years during everyday conversation, your precise age includes months, days, and even smaller units of time. That’s exactly what this tool calculates for you.

How Old Am I Today? Use the Age Calculator

Getting your exact age takes just a few steps:

1. Enter your date of birth in the first field. You can type it directly or use the calendar picker to select your birthday.
2. Add your time of birth if you know it. This is optional — if you leave it blank, the calculator assumes midnight (12:00 AM). Including your birth time gives more accurate results when viewing your age in hours, minutes, or seconds.
3. The “Calculate Age On” field defaults to today’s date and current time. Leave it as-is to find out how old you are right now.
4. Choose your preferred unit from the dropdown. “Years / Months / Days” gives the most natural reading of your age, while options like “seconds” or “milliseconds” reveal some impressively large numbers.

The calculator instantly displays your result along with a breakdown showing your total days, hours, and minutes alive. It also tells you how many days until your next birthday and what age you’ll be turning.

How to Calculate Age from Date of Birth Manually

Understanding how age calculation works behind the scenes is straightforward. Here’s the manual method, step by step.

Suppose today’s date is 20 March 2026, and you were born on 8 July 1995.

Step 1 — Count the full years. Your most recent birthday was 8 July 2025. From 8 July 1995 to 8 July 2025 is exactly 30 years.

Step 2 — Count the full months. From 8 July 2025, count forward in whole months without going past today. July → August → September → October → November → December → January → February → March 8. That gives you 8 full months, landing on 8 March 2026.

Step 3 — Count the remaining days. From 8 March 2026 to 20 March 2026 is 12 days.

Result: You are 30 years, 8 months, 12 days old.

A few things worth knowing about how the maths works: when calculating in “months” mode, the calculator treats a month as 30.4375 days on average (365.25 ÷ 12). When calculating in “years” mode, it uses 365.25 days per year to account for leap years. The “Years / Months / Days” option gives calendar-exact results by counting from one calendar date to another.

How Many Days, Weeks or Months Old Am I?

Seeing your age in different time units can be genuinely surprising. Most people have a rough idea of their age in years, but far fewer know they’ve been alive for over 10,000 days, or half a million hours.

To find your age in any unit, enter your date of birth, confirm today’s date is in the second field, and select your desired unit from the dropdown. The calculator supports:

• Years / Months / Days — the standard, calendar-accurate breakdown
• Years — your age as a decimal (e.g. 30.7142 years)
• Months — total months lived as a decimal
• Weeks — total complete weeks, plus any remaining days
• Days — total days since birth
• Hours — total hours (more accurate if you include birth time)
• Minutes — total minutes alive
• Seconds — total seconds since you were born
• Milliseconds — for when you want the biggest number possible

How Old Will I Be in 2050?

The age calculator works for future dates just as easily as past ones. To find out how old you’ll be at any point in the future, simply change the “Calculate Age On” field to your target date.

Example: If you were born on 15 June 2000 and want to know your age on New Year’s Day 2050:

Set your date of birth to 15 June 2000, change “Calculate Age On” to 1 January 2050, and the calculator tells you that you’ll be 49 years, 6 months, 17 days old.

This is useful for planning retirement dates, working out eligibility ages for specific milestones, or just satisfying curiosity about how old you’ll be at a future event.

If You Were Born in 1999, How Old Are You?

When you only know the birth year and not the exact date, you can still estimate someone’s age by subtracting the birth year from the current year.

In 2026: 2026 − 1999 = 27

So someone born in 1999 is either 26 or 27 years old in 2026, depending on whether their birthday has already passed this year.

For a precise answer, you’ll need the full date of birth. But this quick subtraction method gets you within one year either way, close enough for most situations.

How Many Days Are in 15 Years?

If you’re 15 years old and wondering “how many days old am I?”, the answer depends on exactly when you were born, because leap years add an extra day every four years.

The simplest way to get the answer is to enter your date of birth and today’s date into the calculator, then select “days” as the unit. For a rough estimate: 15 years contains approximately 5,478 to 5,479 days, depending on how many leap years fall within that span.

To convert any number of years to days, you can use the age calculator by entering two dates that are exactly that many years apart. For instance, 1 January 2010 to 1 January 2025 is 5,479 days.

How Old Was I on a Specific Date?

The calculator isn’t limited to today’s date. You can find out your age on any date in the past by changing the “Calculate Age On” field.

Example: You were born on 12 September 1988, and you want to know how old you were when you graduated university on 30 June 2010.

Enter your date of birth as 12 September 1988, set “Calculate Age On” to 30 June 2010, and the result shows: 21 years, 9 months, 18 days.

This feature is particularly handy for filling in forms that ask for your age at a specific date, working out how old someone was during a historical event, or simply remembering where you were at a certain age.

Frequently Asked Questions

How many days have I been alive?

Enter your date of birth into the age calculator and select “Days” from the unit dropdown. The result shows the total number of days between your birth date and today. For a quick estimate without the calculator, multiply your age in years by 365 and add one day for each leap year you’ve lived through (roughly one every four years).

How many months are in 3 years?

Three years contain exactly 36 months. Every year has 12 months regardless of whether it is a leap year, so you simply multiply the number of years by 12. Five years would be 60 months, ten years would be 120 months, and so on.

How old am I if I am 10,000 days old?

If you are 10,000 days old, you are approximately 27 years and 4 to 5 months old. The exact figure depends on how many leap years fell within that period. Reaching 10,000 days is a milestone some people celebrate, it usually falls around age 27 and a half.

How old am I if I was born in 1983?

As of 2026, someone born in 1983 is either 42 or 43 years old, depending on whether their birthday has already passed this year. To get the precise answer, enter the full date of birth (day, month, and year) into the age calculator.

What year was I born if I’m 21?

If you are 21 years old in 2026, you were born in either 2004 or 2005. If your birthday has already occurred this year, your birth year is 2005. If your birthday is still coming up, your birth year is 2004. Subtract your current age from the current year and adjust by one year depending on whether your birthday has passed.

How old am I if I was born in 1964?

As of 2026, someone born in 1964 is either 61 or 62 years old. The answer depends on whether their birthday has already taken place this calendar year. For the exact age including months and days, use the age calculator above with the full date of birth.

How many weeks old am I?

To find your age in weeks, enter your date of birth into the calculator and select “Weeks” from the dropdown menu. It will show the total number of complete weeks you have lived, along with any remaining days. As a rough guide, one year contains approximately 52.18 weeks, so a 30-year-old has lived around 1,565 weeks.

Does the age calculator account for leap years?

Yes. The calculator works with actual calendar dates, so every leap year (including its extra day on 29 February) is counted automatically. When displaying age as a decimal number of years, it uses 365.25 days per year to account for the leap year cycle. For the “Years / Months / Days” view, the result is calendar-exact with no averaging.