The way a person’s age is calculated can vary across different cultures. This calculator follows the most widely used age system, where a person’s age increases on their birthday. For instance, someone who has lived for 3 years and 11 months is considered 3 years old, and their age will become 4 on their next birthday, which is one month later. This system is commonly used in most Western countries. In other cultures, age may be counted differently, either 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, a person is born at age 1, and their age increases during the Traditional Chinese New Year rather than on their birthday. For instance, if a baby is born just one day before the Traditional Chinese New Year, they will be considered 2 years old just two days later, even though they are only 2 days old. There are also situations where calculating age in months and days can be confusing, particularly when the starting date is at the end of a month. For example, counting from February 20 to March 20 is considered one month. However, calculating the age from February 28, 2022, to March 31, 2022, can be done in two ways. If February 28 to March 28 is counted as one month, the result is one month and 3 days. If both February 28 and March 31 are treated as the end of their respective months, the result is simply one month. Both methods are valid. Similar scenarios arise with dates like April 30 to May 31 or May 30 to June 30, due to the varying number of days in different months. In this calculator, we use the first method for consistency.