How to calculate the first birthday of leap month?

In leap months, the baby's one-year-old age should be calculated according to the Gregorian calendar, that is, according to the date of birth, not according to the lunar calendar. Because the Gregorian calendar is widely used in China, in western countries, the birth date of Gregorian calendar is usually used to calculate one's full age.

Specifically, if the baby's birthday is before the leap month, its one-year-old age is the number of years from the year of birth to the birthday of the following year; If a baby's birthday is after a leap month, its one-year-old age is the number of years that have passed from the year of birth to the month before the birthday. Every 12 months is the age of 1, and every 12 months is the age of 1, which is counted by days from the day after the birthday.

For example, if a baby was born in June of 202 1 year, then by 2022, its one-year-old age will be1; If the baby was born in July, 20021year, he will be 0 years old by 2022, because he has not yet reached the birthday month.