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Leap Year Calculator

Check if any year is a leap year using Gregorian calendar rules. List all leap years in a date range, find next and previous leap years, and understand why century years are special. Free tool.

Last revised 30 July 2026

By Team GlobalCalqulate · About our editorial standards

Calculation Mode

What would you like to do?

Year Selection

Year

Start Year

End Year

2026

No ✗

Not divisible by 4

Sources & methodology

Formula:: Leap year rule
Reference:: U.S. Naval Observatory
Content last updated:: July 2026
Scheduled re-verification:: July 2027

Calculation type: Exact calculation. Figures are taken from U.S. Naval Observatory — see sources below.

Key Tips

✓
2024 was a leap year. The next leap years are 2028, 2032, 2036, 2040.
✓
Century years like 2100 skip the leap day — they're divisible by 100 but not 400.
✓
If you were born on February 29 (a 'leapling'), you celebrate on Feb 28 or Mar 1 in non-leap years.
✓
The Gregorian calendar was introduced in 1582. Years before that followed the simpler Julian leap year rule (every 4 years).

Formula & methodology

Formula used

Leap year rule

leap if (year ÷ 400 has no remainder) or (year ÷ 4 has no remainder and year ÷ 100 does have one)

Divisible by 4 is a leap year, except centuries, except those divisible by 400. So 2000 was a leap year and 1900 was not.

Why the exceptions exist

tropical year ≈ 365.2422 days

A plain four-year rule overcorrects slightly; skipping three leap days every four centuries brings the calendar back in line.

Variable definitions

Symbol	Meaning	Unit
year	Year. the year being tested	year

Step-by-step calculation

1. Enter a year
The calculator reports whether it is a leap year and which rule decided it.
2. Or set a range
It lists every leap year between the two years given.

Limitations

Applies the Gregorian rule to every year given, including years before the Gregorian calendar was adopted — which happened in different years in different countries.
The Julian calendar, still used by some churches for liturgical dates, has a leap year every four years with no century exception.

This page is educational. It applies the formula described above to the figures you enter and shows the arithmetic behind the result. The output is only as good as the inputs and the assumptions listed here, and it is general information rather than advice about your particular situation.

Sources & references

Introduction to Calendars — leap year rules in the Gregorian calendar — U.S. Naval Observatory

Help & FAQs

Frequently Asked Questions

Clear answers to common questions to help you use this calculator confidently.

What is a leap year?

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A leap year has 366 days instead of 365, adding February 29 to keep the calendar in sync with the Earth's orbit around the sun.

What are the rules for determining a leap year?

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A year is a leap year if it's divisible by 4 — except century years (ending in 00), which must also be divisible by 400. So 1900 was not a leap year, but 2000 was.

Why do we have leap years?

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Leap years correct the drift between the calendar year (365 days) and the actual solar year (approximately 365.2425 days) — without them, the calendar would slowly fall out of sync with the seasons.

What happens if you're born on February 29?

Tap to view the answer

People born on February 29 (leaplings) typically celebrate their birthdays on February 28 or March 1 in non-leap years, since that date doesn't exist most years.

When was the leap year rule established?

Tap to view the answer

The current Gregorian calendar leap year rules were established by Pope Gregory XIII in 1582, refining the earlier Julian calendar's simpler every-4-years rule.

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How to Use This Calculator

Choose a Mode

Check a single year, list all leap years in a range (e.g., 2000–2100), or find the next or previous leap year from any year.

Enter Your Year(s)

For check mode, enter one year. For list mode, enter start and end years. For next/previous, enter a starting year.

Review the Result

See whether the year is a leap year, which rule was applied, how many days are in the year, and listed results.

Understanding Your Results

Leap Year Rule
Divisible by 400? → Yes. Divisible by 4 but NOT by 100? → Yes. Otherwise → No. This three-part rule keeps the calendar aligned with Earth's orbit.
Days in Year
Leap years have 366 days (February gains the 29th). Common years have 365 days.
Century Exception
Years ending in 00 must be divisible by 400 to be leap years. 2000 was a leap year; 1900 was not; 2100 will not be.

Key Tips

✓
2024 was a leap year. The next leap years are 2028, 2032, 2036, 2040.
✓
Century years like 2100 skip the leap day — they're divisible by 100 but not 400.
✓
If you were born on February 29 (a 'leapling'), you celebrate on Feb 28 or Mar 1 in non-leap years.
✓
The Gregorian calendar was introduced in 1582. Years before that followed the simpler Julian leap year rule (every 4 years).

Why Leap Years Exist

The Astronomical Reason

Earth takes approximately 365.2425 days to orbit the Sun — not exactly 365. If we used a strict 365-day calendar, we'd lose about 0.2425 days per year. After 100 years, the calendar would be off by roughly 24 days — nearly a full month. Leap years add one extra day every 4 years to compensate, keeping seasons aligned with calendar months.

The Three-Part Gregorian Rule

The Gregorian calendar uses three conditions: (1) If the year is divisible by 400, it IS a leap year. (2) If the year is divisible by 4 but NOT by 100, it IS a leap year. (3) All other years are NOT leap years. This means 2000 (÷400=5) passes rule 1. 2024 (÷4=506, not ÷100) passes rule 2. 1900 (÷4=475, but ÷100=19 and not ÷400) fails all rules. 2100 will also fail — it's divisible by 100 but not 400.

Why Century Years Are Special

Without the century exception, adding a leap day every 4 years adds slightly too much time — about 11 minutes too much per year, or about 3 days every 400 years. The Gregorian reform addressed this by skipping 3 leap days every 400 years. The skipped years are century years not divisible by 400: 1700, 1800, 1900, 2100, 2200, 2300. This correction keeps the average calendar year at 365.2425 days, matching the solar year to within about 26 seconds per year.

Julian vs Gregorian — The 10-Day Gap

Before 1582, the Julian calendar added a leap day every 4 years without exception. Over 1,600 years, the accumulated drift reached 10 days. Pope Gregory XIII corrected this by decreeing that October 4, 1582 would be followed by October 15, 1582 — skipping 10 days. Not all countries adopted immediately: Britain and its colonies didn't switch until 1752 (skipping 11 days by then). The calculator uses Gregorian rules for all years, including pre-1582 dates.

Formula & methodology

Formula used

Leap year rule

leap if (year ÷ 400 has no remainder) or (year ÷ 4 has no remainder and year ÷ 100 does have one)

Divisible by 4 is a leap year, except centuries, except those divisible by 400. So 2000 was a leap year and 1900 was not.

Why the exceptions exist

tropical year ≈ 365.2422 days

A plain four-year rule overcorrects slightly; skipping three leap days every four centuries brings the calendar back in line.

Variable definitions

Symbol	Meaning	Unit
year	Year. the year being tested	year

Step-by-step calculation

1. Enter a year
The calculator reports whether it is a leap year and which rule decided it.
2. Or set a range
It lists every leap year between the two years given.

Limitations

Applies the Gregorian rule to every year given, including years before the Gregorian calendar was adopted — which happened in different years in different countries.
The Julian calendar, still used by some churches for liturgical dates, has a leap year every four years with no century exception.

Calculator inputs

Calculation Mode

Year Selection

Your results

Sources & methodology

Key Tips

Formula & methodology

Formula used

Leap year rule

Why the exceptions exist

Variable definitions

Step-by-step calculation

Limitations

Sources & references

What is a leap year?

What are the rules for determining a leap year?

Why do we have leap years?

What happens if you're born on February 29?

When was the leap year rule established?

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More everyday calculators

Calculator inputs

Calculation Mode

Year Selection

Your results

Sources & methodology

How to Use This Calculator

Example: Check 2024

Understanding Your Results

Key Tips

Why Leap Years Exist

The Astronomical Reason

The Three-Part Gregorian Rule

Why Century Years Are Special

Julian vs Gregorian — The 10-Day Gap

Formula & methodology

Formula used

Leap year rule

Why the exceptions exist

Variable definitions

Step-by-step calculation

Limitations

Sources & references

How to Use This Calculator

Example: Check 2024

Understanding Your Results

Why Leap Years Exist

The Astronomical Reason

The Three-Part Gregorian Rule

Why Century Years Are Special

Julian vs Gregorian — The 10-Day Gap