Age Calculator

Usage Instructions

If you've arrived here, you likely want to calculate a person's age.

If you know their birthday, you've come to the right place, as thanks to our calculator, you'll be able to know it in a matter of seconds.

You simply must enter the person's date of birth and then press “Calculate Age”.

Now, you might be interested in learning how to do the same calculation by hand. In the following lines, we're going to explain how to do it in a simple and step-by-step manner.

How to calculate the exact age “by hand”

Calculating age involves counting the number of years that have passed since birth until the date we are at this moment.

To perform this operation as accurately as possible, we must take into account both the day and the month of birth.

Now we are going to explain how to do the simple calculation (just years) and how to do the complex one (years, months, and days).

Calculation of years of life

We take the individual's date of birth and the current date.

As before their birthday, the individual has not yet turned years old, we must distinguish between three different possibilities:

1. The current date is after the birthday.
2. The current date coincides with the birthday.
3. The current date precedes the birthday of the current year.

In the first and second cases, the calculation consists simply of calculating the difference between the current year and the year of birth.

In the third case, we will calculate the difference between the current year and the year of birth and subtract one from the result.

The following examples will help you understand how the operation we just described is carried out:

Example 1

Let's imagine that today is March 5, 2018. What will be the age of a person who was born on February 8, 1983?

Given that the current date is after the birthday (February 8, 2018), we are going to limit ourselves to calculating the difference between the current year and the year of birth:

2018 – 1983 = 35

Considering that we are in March and that the person for whom we are finding out the age was born in February, we can conclude that they have already turned 35 years old.

Example 2

Now let's suppose that today is March 20, 2018. How old is a person who was born on August 9, 1983?

As the current date is before the birthday (August 9), we must subtract one year from the result that comes from subtracting both years:

2018 – 1983 = 35

35 – 1 = 34

We can affirm that this person is 34 years old, and will not turn 35 until August 8.

Calculation of chronological age: years, months, and days of age

In this case, it's an operation with a higher degree of precision. Let's remember the three possibilities mentioned before:

1. The current date is after the birthday.
2. The current date coincides with the birthday.
3. The current date is before the birthday of the current year.

In the first case, you should calculate the age as the difference between the current year and the year of birth, and to the result, we will add the difference between the months and days that exist between the current date and the birthday.

In the second case, simply calculate the difference between the current year and the year of birth.

In the third case, we will calculate the age, as in the previous case, and then subtract one year from the result before adding the difference in months and days.

We are going to revisit the previous examples and add the months and days.

Example 1

Let's assume that today is March 5, 2018. What will be the age of a person who was born on February 8, 1983?

First of all, we will calculate the years elapsed between February 8, 1983, and February 8, 2018:

2018 – 1983 = 35

Now it's important to take into account the time elapsed between February 8 and March 5:

• February: 28 – 8 = 20 days.
• March = 5 days.
• 20 + 5 = 25 days.

This person will be 35 years and 25 days old.

Example 2

Now let's imagine that today is March 20, 2018. What will be the age of a person who was born on August 9, 1983?

As the current date is before the birthday, first calculate the years elapsed from August 9, 1983, to August 9, 2017.

2018 – 1983 = 34

At this point, we will calculate the number of days that separate August 9, 2017, from March 20, 2017.

• In August: 31 – 9 = 22 days.
• In September: 30 days.
• In October: 31 days.
• In November: 30 days.
• In December: 31 days.
• In February: 28 days.
• In March: 20 days.

22 + 30 +31 +30 +31 +28 + 20 = 192 days

Therefore, we can conclude that this person is 34 years and 192 days old.

This has been all we could teach you about the exact calculation of ages. In this article, you have learned to use our calculator and to do the same calculation by hand, step by step and always taking into account all the possible combinations that exist.

If you found the article interesting, do not forget to share it with all your contacts on your social networks, thus contributing your bit to this community of free calculators and simulators.

Finally, if in reading the article or in using the age calculator you have found any type of error or miss anything, do not hesitate to use the contact form to let us know.

BS Román Ramos

Bachelor of Mathematics and Master in Operations Research from UCV.

Román Ramos holds a Bachelor's degree in Mathematics from the Central University of ... Read more »