April Fools’ Day probably grew out of older European spring festivals and customs, but its exact origin is still uncertain. The most common explanation is that it became associated with calendar changes in France in the 1500s, when New Year’s Day moved to January 1 and people who kept celebrating in late March or early April were mocked as “April fools.”

Main origin theories

[5] [1][5] [1]
Theory What it says
France and the calendar change When New Year’s Day shifted to January 1, people who stuck with the old date were teased.
Older spring festivals It may be connected to Roman or seasonal celebrations like Hilaria or Holi, which involved merriment and role reversal.
Medieval European custom Clear references to April fooling appear in late medieval and Renaissance Europe, suggesting the tradition was already established by then.

What historians think

Historians generally agree on one thing: nobody knows the single true beginning for sure. The holiday is old, and the evidence points to a mix of folk traditions rather than one clean origin story.

Simple version

So the short answer is: April Fools came from old European springtime joking traditions, and the strongest popular explanation ties it to the switch in New Year’s dates in France.