found a more exact explanation...it depends on the different calendars

 

In Western Christianity, using the Gregorian calendar, Easter always falls on a Sunday between March 22 and April 25 inclusively.[17] The following day, Easter Monday, is a legal holiday in many countries with predominantly Christian traditions. In Eastern Christianity, using the Julian calendar, Easter also always falls on a Sunday from March 22 to April 25 inclusive, which on the Gregorian calendar, due to the 13 day difference between the calendars between 1900 and 2099, are dates from April 4 to May 8 inclusive.