# Age Calculator

Created by Rita Rain
Reviewed by Dominik Czernia, PhD candidate and Jack Bowater
Last updated: Jun 29, 2022

If you've found yourself asking existential questions like "How old am I today?", "How old was I on this date?" or "How old will I be in 2050?", then this age calculator is here to help you.

The exact age calculator lets you choose from a variety of time units - from milliseconds to years - so finally you can get answers to your age-related questions:

• What is my age?
• How many days old am I?
• How many months old am I?
• How many weeks old am I?

In the text, we'll cover examples of time calculations (if you were born in 1999 how old are you, how many days are there in 15 years, how to calculate age from a date of birth, etc.)

Once you've found your chronological age, make sure to also check how old your dog or cat, or pet bird is in human years, and contemplate all the seconds you've spent on planet Earth.

## What is my age?

Age, in general, is the amount of time for which something existed.

A person's age is the time that has passed from the moment they were born. The time before birth is called the gestational age (age of a pregnancy is counted from conception).

In most parts of the world, a baby starts life at 0 and becomes 1 year old on the first anniversary of their birth. However, in some countries (notably in Korea) age is counted differently. In the text we'll use the most common system.

Let's see how to use the age calculator to help you answer the question - "what is my age?".

## How old am I today? Ask the age calculator

How old are you? The easiest way to answer this is to use the age calculator and let it calculate age from your date of birth:

1. In the first field of the age calculator, input your birth date . You can either type it in (input the first three letters of the month's name followed by the day, a comma, and the year, e.g., "Oct 1, 1996"), or click the calendar icon and select the date.

2. If you want to know your exact age in a "small" unit (e.g., you're wondering "how old am I in seconds?"), you can set the time of your birth in the advanced mode. If you leave it empty, the age calculator will count the time from midnight the day you were born.

3. The date in the third field of the age calculator is set to "today". If you want to know your current age ("How old am I today?"), leave it as it is.

4. Select the unit in which you want your result - this lets you answer different questions ("How many months old am I?", "How many weeks old am I?", "How many seconds old am I?").

5. The time is counted from birth till now, including the current time.

The result will be exact if you choose "years/months/days." In this option, we assume that a month passes from the chosen day of the first month to the same day of the second month (e.g., 22.02 to 22.03). If you choose the "months" unit, we will assume that months have 30.4375 days (that's an average). In the "years" option, we assume a year has 365 days (we don't account for leap years).

## How old are you? Calculate age from the date of birth

We'll now learn how to calculate age from date of birth without help from the age calculator.

Let's say it's 15.01.2021 and you were born on 5.12.2000. Let's time-travel and count:

1. Start on your date of birth. Go forward in time - check how many years you have to add to reach to your last birthday:

Your last birthday was on 5.12.2020. Subtract the years:

5.12.2020 - 5.12.2000 = 20 years

2. Now we're on 5.12.2020. Add as many full months as you can but don't go too far into the future (stop before you reach today).

In this example, if we go 1 month forward from 5.12.2020, we land on 5.01.2021 and so have to stop time travelling in months.

3. Add the remaining days. We're on 5.01.2021. We can simply subtract days:

15.01.2021 - 5.01.2021 = 10 days

4. Add the results from steps 1-3. We get 20 years, 1 month and 10 days.

## How many days/weeks/months/... old am I?

This age calculator includes various time units, so it can answer all the strange questions like "How many weeks old am I?", "How many seconds old am I?", "How many days old am I?", etc.

To check your age in different units, enter your date of birth, make sure you have today's date in the second field, and set the desired unit in the last field of the age calculator.

## How old will I be in 2050?

Counting age for future dates works the same as for past dates. In the age calculator, you need to change the default current date (the "Calculate age on" field) to the future date.

Let's say you were born on 4.03.2005. If you're wondering, "How old will I be in 2050?":

1. Set your date of birth (you can type in "Mar 4, 2005").

2. "Calculate age on" should be followed by "Jan 1, 2050" or any other day in 2050, depending on when you want.

3. The age calculator will tell you that on New Year's Day, 2050, you'll be 44 years 9 months 28 days old.

Make sure to also check out our Lunar age calculator and find out your age according to the Chinese and Hijri calendars.

## If you were born in 1999, how old are you?

If you don't know someone's exact date of birth, subtract the year of birth from the current year and the result will be the estimated age (you can be off by one year either side).

For example, now it is 10.01.2021. Let's subtract years:

2021 - 1999 = 22.

So, the answer to "If you were born in 1999, how old are you?" is: "In 2021, you'd be approximately 22 years old". However, if you were born after 10.01, you'd officially become 22 on your birthday. Until then, you'd be 21 in the eyes of the law.

## How many days are there in 15 years?

If you're 15 and wondering, "How many days old am I?", enter your date of birth and today's date into the age calculator. Then choose "days" as the unit.

If you want to convert 15 years to days, you can use our time unit converter or type into this age calculator two dates which are 15 years apart. For example, "Jan 1, 2000" and "Jan 1, 2015" are 5479 days apart.

## Example - "How old was I on this date...

...when I first learned that time is relative?"

You've just found your diary on the attic, opened it on a random page and read:

"3.02.1978

Nothing will ever be the same again. I used to think that time is something like a line going from left to right, on which we travel. I thought it's always the same, whoever and wherever you are. Today Mr. Brown (and I trust his knowledge) said that the faster you move, the slower time passes! 😮 "

You've moved fast, but not fast enough. You've grown old, and it happened so quickly. You've started wondering "How old was I on this date?". You don't have much time for calculations, so you turn to our chronological age calculator:

1. You enter your date of birth. Let's say you were born 25.04.1962.
2. Enter the date from your journal - 3.02.1978 (or type in "Feb 3, 1978").
3. Read the result - you were 15 years 9 months 8 days old...

## FAQ

### How many days have I been alive?

To estimate your age in days:

1. Remind yourself which birthday you celebrated last and multiply this value by 365.
2. Count the number of full months that have passed since your last birthday and multiply it by 31, e.g., if you were born on September 15th, the first full month ends on October 15th.
3. Determine the number of days since the last full month.
4. Estimate the number of leap years you've experienced (every year that divides by four).
5. Sum up all of the above values.
6. Subtract 1 for each of these full months (since your last birthday): April, June, September, November, and subtract 3 for February.
7. Congratulate yourself and celebrate being this many days old!

### How many months do 3 years have?

Three years contain precisely 36 months. Each year contains 12 months, whether it's a leap year or not.

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

You are 27 years and 138 or 139 days old. It depends on whether 7 or 6 leap years (the February of those years, to be precise) have already passed. We can also say you're 27 years, 4 months, and between 15 to 19 days old (depending on which months have passed).

### How many years ago was 2017?

The year 2017 was four years ago, assuming it's 2021. In 2022, this period will extend to 5 years.

### How old am I if I was born in 1983?

You are 37 or 38 years old as of 2021. The exact number depends on whether you've celebrated your birthday this year or not. If you haven't, you're 37. If you have, you're 38.

### What year was I born if I'm 21?

As for 2021, you were born in 2000 if you've already celebrated your birthday this year. Otherwise, you were born in 1999.

### How old am I if I was born in 1964?

You are 56 or 57 years old as of 2021. The exact number depends on whether you've celebrated your birthday this year or not. If you haven't, you're 56. If you have, you're 57.

Rita Rain
Date of birth
Calculate age on
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