This article will explain **how to calculate leap year **as well as some other interesting facts about leap years.

## How to calculate leap year

Very simple to see if a specific year is a leap year or not. To calculate if a specific year is a leap year:

Take the year and divide it by 4.

If the answer of division is equal to a whole number, the year is a leap year.

If the answer to the division is not equal to a whole number, the year is not a leap year.

**Example One:**

**Year : 1983 : **

**1983/4 = 495.75**

**495.75 is not a whole numbers as .75 is a fraction.**

**Thus 1983 is not a leap year.**

**Example Two:**

**Year : 2004 :**

**2004/4 = 501**

**501 is a whole number**

**Thus 2004 is a leap year.**

**Leap year **rules and calendar accuracy

## How to calculate leap year Formula:

### What Is a Leap Year?

Leap years are years where an extra, or intercalary, day is added to the end of the shortest month, February. The intercalary day, February 29, is commonly referred to as leap day.

Leap years have 366 days instead of the usual 365 days and occur almost every four years.

### Why do we need leap years?

The Gregorian calendar, which now serves as the standard calendar for civil use throughout the world, has both common years and leap years. A common year has 365 days and a leap year 366 days, with the extra–or intercalary–day designated as February 29. A leap year occurs every four years to help synchronize the calendar year with the solar year, or the length of time it takes the earth to complete its orbit around the sun, which is about 365Â¼ days.

The length of the solar year, however, is slightly less than 365Â¼ days-by about 11 minutes. To compensate for this discrepancy, the leap year is omitted three times every four hundred years.

In other words, a century year cannot be a leap year unless it is divisible by 400. Thus 1700, 1800, and 1900 were not leap years, but 1600, 2000, and 2400 are leap years.

**How to calculate leap year: Divide by 4: Whole number is leap years: Fractions is not leap years**

### What are your chances of being born on leap day?

About 1 in 1,500.

### How to calculate leap year – When is the birthday party?

If you are born on a Leap Year, can you get your driver’s license as early as February 28th? Well, each state decides whether or not February 28 or March 1 will be the day you are eligible to get your license. Most states, however, consider March 1st the official day. For instance, the Michigan Vehicle Code states that people born on February 29th “are deemed to have been born on March 1st.” Another fun fact: Leap year babies yet their driver’s licenses when they are officially four years old (16)! There are no rules on when you have a party, however, so really in day in February or March is fair game to celebrate a leap year birthday.

### How many people were born on leap day?

There are about 187,000 people in the US and 4 million people in the world who were born on Leap Day.

### The rules for determining a leap year

Most years that can be divided evenly by 4 are leap years.

**Exception:** Century years are NOT leap years UNLESS they can be evenly divided by 400.

### How to calculate leap year – When did leap year originate?

The Gregorian calendar is closely based on the Julian calendar, which was introduced by Julius Caesar in 45 BC. The Julian calendar featured a 12-month, 365-day year, with an intercalary day inserted every fourth year at the end of February to make an average year of 365.25 days. But because the length of the solar year is actually 365.242216 days, the Julian year was too long by .0078 days (11 minutes 14 seconds).

This may not seem like a lot, but over the course of centuries it added up. Until in the 16th century, the vernal equinox was falling around March 11 instead of March 21. In 1582, Pope Gregory XIII adjusted the calendar by moving the date ahead by 11 days and by instituting the exception to the rule for leap years. This new rule, whereby a century year is a leap year only if divisible by 400, is the sole feature that distinguishes the Gregorian calendar from the Julian calendar.

Following the Gregorian reform, the average length of the year was 365.2425 days, an even closer approximation to the solar year. At this rate, it will take more than 3,000 years for the Gregorian calendar to gain one extra day in error.

**How to calculate leap year: Divide by 4: Whole number is leap years: Fractions is not leap years**

### How to calculate leap year – A Quick History Lesson

The Egyptians were the first to come up with the idea of adding a leap day once every four years to keep the calendar in sync with the solar year. Later, the Romans adopted this solution for their calendar, and they became the first to designate February 29 as the leap day.

### But Wait! It’s Not Quite that Simple!

The math seems to work out beautifully when you add an extra day to the calendar every four years to compensate for the extra quarter of a day in the solar year. As we said earlier, however, the solar year is *just about* 365 ¼ days long, but not exactly! The exact length of a solar year is actually 11 minutes and 14 seconds less than 365 ¼ days. That means that even if you add a leap day every four years, the calendar would still overshoot the solar year by a little bit—11 minutes and 14 seconds per year. These minutes and seconds really start to add up: after 128 years, the calendar would gain an entire extra day. So, the leap year rule, “add a leap year every four years” was a good rule, but not good enough!

### Calendar Correction, Part II

To rectify the situation, the creators of our calendar (the Gregorian calendar, introduced in 1582) decided to omit leap years three times every four hundred years. This would shorten the calendar every so often and rid it of the annual excess of 11 minutes and 14 seconds. So in addition to the rule that a leap year occurs every four years, a new rule was added: a century year is not a leap year unless it is evenly divisible by 400. This rule manages to eliminate three leap years every few hundred years.

### It’s Smooth Sailing for the Next 3,300 Years

This ingenious correction worked beautifully in bringing the calendar and the solar year in harmony, pretty much eliminating those pesky extra 11 minutes and 14 seconds. Now the calendar year and the solar year are just about a half a minute off. At that rate, it takes 3,300 years for the calendar year and solar year to diverge by a day.