Is 2027 a Leap Year?

2027 is not a leap year

The rule has three clauses, and only the third catches anyone out. A year is a leap year if it divides by 4; except that a century year is not, unless it also divides by 400. 2027 does not divide by 4 (2027 / 4 = 506.75), so it does not have a 29 February and 365 days.

2000 was a leap year and 1900 was not, for exactly this reason — the pair of them is the cleanest demonstration of the rule, and the source of a well-known class of software bug. The next leap year after 2027 is 2028. A date in 2027 moves forward one weekday into 2028, unless the span crosses a 29 February.

The rule has three clauses because the tropical year is about 365.2422 days long, not 365.25. Adding a day every four years overshoots by roughly eleven minutes a year, which is three days every four centuries — so the Gregorian reform dropped three leap days per 400 years by skipping the century years that do not divide by 400. That is the whole of it, and 2027 is not in the set that keeps its extra day.

What it means in practice: there is no 29 February in 2027, so a monthly or yearly anniversary that would land there clamps back to 28 February. That clamping rule is the same one the date calculator applies to every month end, and it is written out on the methodology page.

2027 at a glance

Every convention used above — whether the start date counts, how month ends are clamped, which holidays close an office — is written out on the methodology page, including the ISO 8601 week rule and the leap-year rule in full.