Ayyám-i-Há refers to a period of intercalary days in the Baháʼí calendar, when Baháʼís celebrate the Festival of Ayyám-i-Há. The four or five days of this period are inserted between the last two months of the calendar (Mulk and ʻAláʼ). The length of Ayyám-i-Há varies according to the timing of the following vernal equinox so that the next year always starts on the vernal equinox. The 2021 dates for this observance are from sunset on Wednesday, February 24, to sunset on Sunday, February 28.