Age can be calculated differently depending on cultural traditions. This calculator uses the most common age system, where a person’s age increases on their birthday each year. For instance, someone who has lived for 3 years and 11 months is considered 3 years old, and they will turn 4 on their next birthday. This system is widely used in most parts of the world.

However, in some cultures, age is measured differently. In certain systems, age is counted by the number of calendar years a person has lived in, regardless of whether their birthday has occurred. For example, someone who is 20 years old might also be described as being in their 21st year. In one traditional Chinese age system, a person is considered 1 year old at birth, and their age increases not on their birthday, but at the Traditional Chinese New Year. So, if a baby is born just one day before the New Year, they would be considered 2 years old only two days after birth.

When it comes to calculating months and days, results can sometimes seem confusing—especially if the starting date falls at the end of a month. For example, the time from February 20 to March 20 is considered one month. But for a period like February 28, 2022, to March 31, 2022, there are two valid interpretations:

• If we consider February 28 to March 28 as one month, the result is one month and 3 days.

• If we treat both February 28 and March 31 as the ends of their respective months, the result is exactly one month.

Both methods are reasonable, and similar situations arise with date ranges like April 30 to May 31 or May 30 to June 30, due to the varying lengths of months. This calculator follows the first method for consistency.