Which calendar uses the Chinese New Year date that can fall between January 21 and February 20?

The lunisolar calendar determines the Chinese New Year date, which can fall between January 21 and February 20 in the Gregorian calendar.

Chinese New Year, also called the Lunar New Year or Spring Festival, begins on the first day of the first month of the traditional Chinese calendar. That calendar combines lunar months with adjustments tied to the solar year, so its New Year's Day moves relative to the Gregorian calendar.

A typical lunar month lasts about 29.5 days, while a solar year is longer. To keep the calendar aligned with the seasons, an extra intercalary month is inserted in some years. This is why the holiday does not occur on the same Gregorian date annually.

Calling the holiday simply “the Chinese New Year” can obscure related New Year celebrations in other East and Southeast Asian cultures. The date range given here describes the Chinese calendar's New Year in the modern Gregorian system, not every lunar-calendar festival.