The International Day of Mathematics (IDM) is a worldwide celebration. Each year on March 14 all countries will be invited to participate through activities for both students and the general public in schools, museums, libraries and other spaces.

March 14 was chosen as the date for the IDM because it was already celebrated in many countries as Pi Day, based on the fact that some countries write it as 3/14 and the mathematical constant Pi is approximately 3.14.

The International Day of Mathematics project is led by the International Mathematical Union with the support of numerous international and regional organizations from all over the world. It was proclamated by UNESCO on the 40th session of the General Conference, November 26, 2019. The first celebration will be held on March 14, 2020.