Calculating someone's age based on their date of birth might seem like a simple task, but it can be tricky if you don't know where to start. Luckily, with a few basic calculations, you can easily determine someone's age. In this blog, we'll explain how to calculate someone's age based on their date of birth.
Step 1: Determine the current date
The first step in calculating someone's age is to determine the current date. The current date is the date you want to compare the person's date of birth to. For example, if you want to determine someone's age as of April 15, 2023, then April 15, 2023, is the current date.
Step 2: Determine the person's date of birth
The next step is to determine the person's date of birth. This is the date the person was born. You will need to know the month, day, and year of the person's birth.
Step 3: Calculate the person's age
To calculate the person's age, you need to subtract the person's date of birth from the current date. The result will be the person's age in days, weeks, months, or years, depending on how you want to express it. As the calculation can be a bit hectic for you, you can always use an online tool to "Calculate Age from Date of Birth" and the tool will do the rest for you.
Practically, To express the person's age in years, you would divide the number of days by the number of days in a year. There are 365 days in a year, except in a leap year when there are 366 days. To determine if a year is a leap year, you need to consider whether the year is divisible by 4. If it is, then it is a leap year unless it is also divisible by 100. If a year is divisible by 100, it is not a leap year unless it is also divisible by 400. For example, 2000 was a leap year because it is divisible by 4, 100, and 400.
Using the example above, we can calculate the person's age in years as follows:
8,031 days 365.25 (average number of days in a year) = 22 years (rounded to the nearest whole number)
So the person's age as of April 15, 2023, is 22 years old.
Step 4: Handle special cases
There are a few special cases to consider when calculating someone's age. These include:
- If the person has not yet had their birthday this year, you need to subtract one from their age in years. For example, if the person's date of birth is December 31, 2000, and the current date is April 15, 2023, you would calculate their age as follows:
April 15, 2023 - December 31, 2000, = 8,201 days
8,201 days 365.25 = 22.44 years (rounded to two decimal places)
Since the person has not yet had their birthday in 2023, you would subtract one from their age, making them 21 years old.