When is the next leap year? Here are some fascinating leap year facts, along with all the details about why leap day always falls on Feb. 29.

Every fourth year, those extra quarter-days get added to the calendar to ... year has 366 days! 3 A leap year happens when the year can be divided exactly by four (eg 2020 ÷ 4 = 505) – but ...

Since it takes a little over 365 days to complete a full orbit, over time the calendar days won’t match up. Adding a leap day — Feb. 29 — every fourth year keeps everything aligned.