Why Do We Call It a “Leap Year”?


Every four years, an extra day is added to the month of February resulting in 366 days in the calendar year instead of 365. Such years are called leap years. But where does the phrase leap year come from?

In 365-day years, known as common years, fixed dates advance one day in the week per year. For example, Christmas fell on a Thursday in 2014 and will fall on a Friday in 2015. With the insertion of a leap day, dates advance two days instead of one. In 2016, which is a leap year, Christmas will leap over Saturday to fall on a Sunday.

The Gregorian calendar, modified from the Julian calendar used by the Romans, is the current standard calendar used by most of the world. In order to keep the common calendar cycle synchronized with the seasons, one extra day is added to a year. The addition of one day to the calendar every four years is intended to compensate for the fact that 365 days is actually six hours shorter than a solar year.


  1. Hanna Sane -  April 9, 2013 - 9:14 pm

    Today, I went to the beach front with my children. I found a sea shell and gave it to my 4 year old daughter and said “You can hear the ocean if you put this to your ear.” She put the shell to her ear and screamed. There was a hermit crab inside and it pinched her ear. She never wants to go back! LoL I know this is completely off topic but I had to tell someone!

  2. El Gato -  February 29, 2012 - 2:32 pm

    How about sidereal days? Did you know that the rotation of the earth through 360 degrees is a sidereal day and not a regular (solar) day? This is because during a solar day, the earth has moved in its orbit a bit and so must turn a few degrees beyond 360 in order to have the sun above the same spot on the earth. A sidereal day uses a remote star as the reference point.

  3. euroangel -  February 28, 2012 - 2:04 pm

    my friend was born on a leap year..she celebrates her birthday every 28 of february..thanks for this info here.

  4. Fat Boy -  May 11, 2011 - 6:06 pm

    yes it is!!!!!!!!!!!!!!!!

  5. Fat Boy -  March 15, 2011 - 2:28 pm

    wow jace that is random but cherub is AWESOME!!!!!!!!!!!!!!

  6. wordjunkie -  March 1, 2011 - 4:14 pm

    um….Nate? The year 2000 was a leap year.

  7. Jace -  March 1, 2011 - 8:13 am

    read CHERUB

  8. Fat Boy -  March 1, 2011 - 8:12 am

    I’m awesome because my birthday is on feb29th

  9. ... -  March 1, 2011 - 2:33 am

    i think if you birthday is on feb 29 you just celebrate it on the 28 when its not leap year

  10. random 9th grader! -  February 28, 2011 - 1:32 pm

    This is interesting. I’m not really the type that likes stuff like this but this was very informative. I like articles like this! And my baby neice was born in 2000… But if someone was born tomorrow, would that make them a leaper?

  11. nate -  February 28, 2011 - 1:18 pm

    How ’bout telling the world WHY the year 2000 was not a leap year??

  12. Joseph -  February 28, 2011 - 11:54 am

    To Mr.Anderson: The Mayan calender does not predict the end of life. It is only the sick-minded that say that. I hope you are not one of them. Scholars who know the Mayan hieroglyphs say that there is no end predicted there. The calender basically ends there, but the Maya did not build an infinite calender.
    I would like to learn more about the Mayan calender.

  13. Ray -  February 28, 2011 - 11:49 am

    1. RE: Ashley on February 28, 2011 at 1:33 am

    You might– celebrate at exactly the stroke of midnight, so that your party falls between Feb. 28th and Mar. 1st., and only 29′ers would have the right time…!

    2. RE: D Williamson on February 28, 2011 at 7:12 am

    Once upon a time, 365.2425 days/year was correct– ca the era of Adam and Eve, But– the Earth’s rotation also slowly slows, so it’s no longer so correct…!

    (But, should we suppose that Pope Gregory XIII actually knew this slight fact…?)

    3. And for the digitally inclined, Notice also that, had we a binary calendar, we’d have more accuracy yet– as, 365 + (1/4) – (1/128) = 365.24219, right-on today!

    (That’s 1 0110 1101.0011 1110 days/year in fixed-point-Binary representation.)

    REF: The slowing of Earth rotation is attributed to lunar tidal-drag, (which must mean sea level on an east coast is slightly higher than on a west coast, but this does not change mass-weight-constancy at sea level, around the world), at the rate of 5-6 msec-per-year per year, or 60-70 μ-day-per-year per millennium….

  14. astro -  February 28, 2011 - 10:38 am

    Technically, the next leap-day is one revolution around the sun (one earth year) away, not one solar rotation (~25 days) away.

  15. Maddi -  February 28, 2011 - 9:26 am

    i was born on a leap year. Did u know that most people born in leap years are smarter than those who are not?

    (all of this was a LIE) (I hatien you)

  16. Jace -  February 28, 2011 - 7:49 am


    And as I understand, leap year rules are -slightly- more complicated.

    If the year is evenly divisible by 4 – you have leap year.
    The year is evenly divisible by 100, then NO leap year
    The year is evenly divisible by 1000, then you DO have a leap year

    Thus, 2012 IS a leap year, 1900 was Not, but 2000 WAS.

  17. D Williamson -  February 28, 2011 - 7:12 am

    Years that are evenly divisible by 100 are not leap years, unless they are also evenly divisible by 400, in which case they are leap years. For example, 1600 and 2000 were leap years, but 1700, 1800 and 1900 were not. Similarly, 2100, 2200, 2300, 2500, 2600, 2700, 2900 and 3000 will not be leap years, but 2400 and 2800 will be. By this rule, the average number of days per year will be 365 + 1/4 − 1/100 + 1/400 = 365.2425, which is 365 days, 5 hours, 49 minutes, and 12 seconds. – from Wikipedia

  18. Liza with a Z -  February 28, 2011 - 6:27 am

    If February 29 is the day when woman can propose marriage to a man, does that means it’s also known as Sadie Hawkins Day?

  19. MOOT -  February 28, 2011 - 5:30 am

    If Dogpatch Day fell on 29 Feb the guys wouldn’t have a chance.

  20. meleagrid -  February 28, 2011 - 2:28 am

    By the Metonic cycle, this year is a leap year. Those who depend on the supposedly more accurate lunar calendar would agree with that. An extra month is added at certain intervals and in 19 year cycles to produce a calendar where the dates always are supposed to be the same day. For example, if one was be born on a Saturday, that person would always celebrate the birthday on a Saturday the same time of the year every year. Calendars and time they measure are rather complex, but over the centuries they have been refined. Too really find why this came about and why it so, read more about. It’s all in the math. Wikipedia, of course, has a pretty good discussion.

  21. thabo andrew mpheqeke -  February 28, 2011 - 1:41 am

    somewhat abtract.somhow interesting and mind-boggling, but it’s astronomy where time is the central focus. come up with more articles of this nature.

  22. Ashley -  February 28, 2011 - 1:33 am

    Hi. My name is Ashley. Dictionary.com, I really like your post. Pretty cool. My friend Kylie was born on Feb 29, 2000. Technically she’s only two. But we still celebrate her birthday on the 28th if it’s not a leap year. This article is so awesome because now I can call her a leaper! Yay! Cool! Actually I think today is the 28th…yeah that’s right! I celebrated Kylie’s sort-of birthday today…we had some cake! I can’t wait till next year…Kylie will be “three”! But we still count her as eleven. I really like her. And I really like your article, Dictionary.com! Thanks for sharing. Especially since it finally has nothing to do with Spain!

    Bye for now
    –Ashley :)

    PS Pinch and a punch for the last day of the month

  23. Lucia -  February 28, 2011 - 1:18 am

    Hm, but the article is not exactly correct. Leap years that end a century happen only every 400 years. That is, 2000 was a leap year and 2100 will be not, the next secular leap year will be 2400. That’s because the time lost every 365 days is not exactly 6 hours… that would be too easy!

  24. Mr.Anderson -  February 28, 2011 - 1:06 am

    Very good artical !But just wanted to know did the miayian calender also have leap years if not how could they predict that life as we know it would end in 2012 ???????

  25. TrulyMe -  February 27, 2011 - 7:31 pm

    The revised Bangla calendar mimics the Gregorian one? I never knew.

  26. TrulyMe -  February 27, 2011 - 7:30 pm

    LOL. Nice article. That was one smart five year old! :P

  27. ivorybrunette -  February 27, 2011 - 6:26 pm

    Guess I’m the first. The only thing I have to say is that for all I’ve been hearing lately about the “wide-ly held tradition” of a woman proposing to a man on a leap day, I had never known about this not too long ago. Can anyone tell me when this started and how?

  28. Eyewitness -  February 27, 2011 - 5:59 pm

    Leapin’ Lizards! You mean February 29th isn’t an orphan?

  29. Ray -  February 27, 2011 - 5:46 pm

    That’s all fine-and-dandy for those who live in Romanized countries… But in the Grecized countries they do a bit differently– the semiofficial Orthodox calendar since 1924, replaced the 400th-rule by more-accurate 200th-or-600th-modulo-900…. However, we shouldn’t-need worry about this until A.D. 2800….


    * Rumania (Romania) is purportedly included with the Greek, despite its name.

    REF: http://adsabs.harvard.edu/full/1946MNSSA…5….6B

  30. Jane -  February 27, 2011 - 5:29 pm

    I love this post. My FIL was born on 29 February but I always understood him to be a ‘leapling’, not a ‘leaper’. Have you heard of that one?

  31. Bob -  February 27, 2011 - 5:09 pm

    woah that’s very interesting but next time state the actual fact that was proposed in the title, THEN go on to related facts please!!!

  32. Steve Osuman -  February 27, 2011 - 4:34 pm

    This is a nice piece of knowledge. I now know why 29february is called a leap day and those born on such days are called ‘leapers’.

  33. Queen Sardonic -  February 27, 2011 - 2:46 pm

    YES! An article NOT about Spain. I mean, I love Spanish as much as the next person, but one can only take so much Espanol.

    I loved this article! Keep up the good work!


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