how is easter determined catholic?

how is easter determined catholic?
Specifically, Easter is celebrated on the first Sunday following the full Moon that occurs on or just after the spring equinox. Yes, it's a bit confusing at first read! Let's break it down: In 2021, the spring equinox happens on Saturday, March 20. The first full Moon to occur after that date rises on Sunday, March 28.
Full answer in: www.almanac.com