Dates
Leap Year Checker
Check whether any year is a leap year, and see the next and previous ones.
Leap Year Checker
2026 is not a leap year
Previous leap year: 2024. Next leap year: 2028.
"Every 4 years" is the rule most people learn, and it's incomplete: the real Gregorian rule has a century-year exception built in specifically to fix a small but real overcounting problem the simpler rule creates.
Software developers are a genuinely common real audience for this specific tool, since off-by-one leap-year bugs (assuming every 4th year is a leap year without checking the century-year exception) are a real, recurring category of date-handling bug in production software, not just a trivia point.
How the Leap Year Checker works
A year is a leap year if it's divisible by 4 — except years divisible by 100, which are NOT leap years — except years divisible by 400, which ARE leap years after all. This three-tier rule exists because the simpler "every 4 years" (Julian calendar) rule adds slightly too many leap days over long stretches, which is exactly why the Julian calendar had drifted about 10 days out of alignment with the seasons by 1582.
This single rule is the quiet foundation underneath a surprising number of the site's other tools — Days in a Month, Days in a Year, the Week Number Calculator's 53-week-year determination, and the Next Birthday Weekday Finder's weekday-shift pattern all ultimately depend on correctly knowing which years are leap years.
Worked example
1900 was NOT a leap year, even though it's divisible by 4, because it's divisible by 100 but not by 400. 2000 WAS a leap year, because 2000 ÷ 400 = 5 exactly. 2100 will NOT be a leap year, for the same reason as 1900 — a distinction most people never encounter in daily life but that genuinely changes date-math results near century boundaries.
Edge cases this tool handles correctly
- Century years are the whole reason for the exception
- Every non-century year divisible by 4 is simply a leap year with no further check needed — the extra two tiers of the rule exist only to handle century years correctly.
- The next leap century
- The next time a century year is a leap year is 2400 (since 2400 ÷ 400 = 6 exactly) — 2100, 2200, and 2300 will all be skipped.
- Downstream effects elsewhere on the site
- Whether a given year is a leap year determines February's day count (Days in a Month), that year's total day count (Days in a Year), whether it can have an ISO week 53 (Week Number Calculator), and the weekday-shift pattern (Next Birthday Weekday Finder, Perpetual Calendar) — all powered by this same rule.
- Checking years far in the past or future
- The three-tier divisibility rule applies uniformly no matter how far back or forward the year is, since it's a fixed mathematical test rather than a table that could run out of pre-computed entries.
- Checking a range of years at once
- The tool checks one year at a time; scanning a range of years for which ones are leap years means checking each individually, applying the same three-tier rule to every year in the range.
- Why the rule targets 365.2425 instead of the true solar year
- The actual mean tropical solar year is closer to 365.2422 days, meaning the Gregorian rule's 365.2425-day average still overcounts very slightly — by roughly one day every 3,300 years — a genuinely tiny residual drift that the calendar's designers accepted as a practical trade-off rather than adding a further, more complex correction tier.
Frequently asked questions
Is every year divisible by 4 automatically a leap year?
No — century years (divisible by 100) also need to be divisible by 400, or they're not a leap year despite being divisible by 4.
Does the Gregorian rule perfectly match the real solar year?
Almost, but not exactly — the true solar year is closer to 365.2422 days, so the Gregorian calendar's 365.2425-day average still drifts by about one day every 3,300 years, a residual gap its designers accepted as good enough rather than adding further correction rules.
Was the year 2000 a leap year?
Yes, because 2000 is divisible by 400.
Why does this three-part rule exist at all?
To keep the calendar year's long-run average (365.2425 days under this rule) close to the real solar year, correcting the Julian calendar's simpler rule, which drifted noticeably over centuries.
Will 2100 be a leap year?
No — it's divisible by 100 but not by 400, the same exception that made 1900 a non-leap year.
Can it check very old or very far-future years?
Yes — the divisibility rule is a fixed mathematical test, not a bounded lookup table, so it works the same way for any year.
Can I check whether the current year is a leap year without knowing the exact year number?
The tool defaults to checking the current year automatically, in addition to letting you enter any other specific year.