Age can be calculated differently across various cultures. This calculator follows the most widely used system, where a person’s age increases on their birthday. For instance, if someone is 3 years and 11 months old, their age would be considered 3, and it would increase to 4 on their next birthday, one month later. This is the system commonly used in most Western countries.

However, in some cultures, age is counted differently. In some places, people calculate age by including or excluding the current year. For example, a person who is 20 years old might be considered the same age as someone in their 21st year of life. In traditional Chinese age systems, people are considered 1 year old at birth, and their age increases at the Chinese New Year, not on their birthday. So, a baby born just one day before the Chinese New Year would be considered 2 years old two days later, even though they are only 2 days old.

In certain cases, the age results from this calculator might be confusing, especially when the starting date falls at the end of the month. For example, we typically consider Feb. 20 to Mar. 20 as one month. However, there are two ways to calculate age from Feb. 28, 2022 to Mar. 31, 2022. One way is to count from Feb. 28 to Mar. 28 as one month, which would make the result 1 month and 3 days. The other way is to treat both Feb. 28 and Mar. 31 as the end of the month, in which case the result is just one month. Both approaches are reasonable. This kind of confusion can also happen with other dates like Apr. 30 to May 31 or May 30 to June 30. The reason for this is the varying number of days in different months. In our calculations, we follow the first method.