A person who was born on February 29 may be called a "leapling". In non-leap years they may celebrate their birthday on February 28 or March 1.

For legal purposes, their legal birthdays depend on how different laws count time intervals. In England and Wales the legal birthday of a leapling is February 28 in common years (see Leap Years, above). In Taiwan the legal birthday of a leapling is also February 28 in common years. In both cases, a person born on February 29, 1992 would have legally reached 18 years old on February 28, 2010.

"If a period fixed by weeks, months, and years does not commence from the beginning of a week, month, or year, it ends with the ending of the day which proceeds the day of the last week, month, or year which corresponds to that on which it began to commence. But if there is no corresponding day in the last month, the period ends with the ending of the last day of the last month.^[3]"

There are many instances in children's literature where a person's claim to be only a quarter of their actual age turns out to be based on counting their leap-year birthdays. A similar device is used in the plot of Gilbert and Sullivan's 1879 comic opera The Pirates of Penzance: As a child, Frederic was apprenticed to a band of pirates until the age of 21. Now, having passed his 21st year, he leaves the pirate band and falls in love. However, it turns out that the pirate indenture says that his apprenticeship does not end until his 21st birthday, and since he was born on February 29, that day will not arrive until he is in his eighties, and so he must leave his fiancée and return to the pirates.

The only notable person known to have both been born and died on February 29 was Sir James Wilson (1812-1880), Premier of Tasmania.

• 1468 – Pope Paul III (d. 1549)
• 1692 – John Byrom, English poet (d. 1763)
• 1724 – Eva Marie Veigel, ballet dancer and wife of actor David Garrick (d. 1822)
• 1736 – Ann Lee, American founder of Quakers (d. 1784)
• 1792 – Gioacchino Rossini, Italian composer (d. 1868)
• 1812 – Sir James Wilson, Premier of Tasmania (d. 1880)
• 1840 – John Philip Holland, Irish inventor (d. 1914)
• 1852 – Frank Gavan Duffy, Australian judge (d. 1936)
• 1860 – Herman Hollerith, American statistician (d. 1929)
• 1896 – Morarji Desai, Prime Minister of India (d. 1995)
• 1896 – William A. Wellman, American film director (d. 1975)
• 1904 – Jimmy Dorsey, American bandleader (d. 1957)
• 1904 – Pepper Martin, baseball player (d. 1965)
• 1904 – Rukmini Devi Arundale, Indian dancer and founder of Kalakshetra (d. 1986)
• 1908 – Balthus, French-Polish painter (d. 2001)
• 1908 – Dee Brown, American writer (d. 2002)
• 1908 – Alf Gover, English cricketer (d. 2001)
• 1916 – Dinah Shore, American singer and actress (d. 1994)
• 1920 – Arthur Franz, American actor (d. 2006)
• 1920 – James Mitchell, American actor
• 1920 – Michèle Morgan, French actress
• 1920 – Howard Nemerov, American poet (d. 1991)
• 1920 – Ivan Petrov, Russian operatic bass (d. 2003)
• 1924 – Al Rosen, American baseball player
• 1924 – David Beattie, New Zealand Governor-General (d. 2001)
• 1924 – Carlos Humberto Romero, President of El Salvador
• 1928 – Joss Ackland, English actor
• 1928 – Terry Lewis, Australian police commissioner
• 1928 – Tempest Storm, American burlesque performer
• 1932 – Jaguar, Brazilian cartoonist
• 1932 – Gene Golub, American mathematician (d. 2007)
• 1932 – Masten Gregory, American F1 Driver (d. 1985)
• 1932 – Reri Grist, African-American coloratura soprano
• 1936 – Jack Lousma, American astronaut
• 1936 – Henri Richard, Canadian ice hockey player
• 1936 – Alex Rocco, American actor
• 1940 – Ecumenical Patriarch Bartholomew I of Constantinople
• 1940 – William H. Turner, Jr. American horse trainer
• 1944 – Phyllis Frelich, American actress
• 1944 – Dennis Farina, American actor
• 1944 – Paolo Eleuteri Serpieri, Italian illustrator
• 1944 – Ene Ergma, Estonian politician
• 1948 – Jirō Akagawa, Japanese novelist
• 1952 – Sharon Dahlonega Raiford Bush, American television personality
• 1952 – Tim Powers, American writer
• 1952 – Raisa Smetanina, Russian cross-country skier
• 1952 – Bart Stupak, American congressman
• 1956 – Jonathan Coleman, Anglo-Australian entertainer
• 1956 – Bob Speller, Canadian politician
• 1956 – Aileen Wuornos, American serial killer (d. 2002)
• 1956 – J. Randy Taraborrelli, American celebrity journalist
• 1956 – Jerry Fry, Baseball player
• 1960 – Ian McKenzie Anderson, British musician
• 1960 – Khaled, Algerian raï musician
• 1960 – Richard Ramirez, American serial killer
• 1960 – Tony Robbins, American motivational speaker
• 1964 – Lyndon Byers, Canadian hockey player and Boston radio personality
• 1968 – Suanne Braun, South African actress
• 1968 – Chucky Brown, American basketball player
• 1968 – Pete Fenson, American curler
• 1968 – Naoko Iijima, Japanese actress
• 1968 – Gonzalo Lira, Chilean-American novelist
• 1968 – Bryce Paup, American football player
• 1968 – Wendi Peters, British actress
• 1968 – Eugene Volokh, American law professor
• 1968 – Frank Woodley, Australian comedian
• 1972 – Antonio Sabàto, Jr., Italian-born actor
• 1972 – Dave Williams, American singer (Drowning Pool) (d. 2002)
• 1972 – Saul Williams, American rapper, poet, and actor
• 1972 – Pedro Zamora, Cuban-born American Real World housemate and AIDS activist (d. 1994)
• 1972 – Iván García, Cuban athlete
• 1976 – Ja Rule, American rapper and actor
• 1976 – Emma Barton, English actress
• 1976 – Terrence Long, American baseball player
• 1980 – Simon Gagné, Canadian ice hockey player
• 1980 – Taylor Twellman, American soccer player
• 1980 – Clinton Toopi, New Zealand rugby league footballer
• 1980 – Chris Conley, American musician
• 1980 – Ruben Plaza, Spanish cyclist
• 1980 – Michail Mouroutsos, Greek Olympic taekwondo gold medalist
• 1984 – Cam Ward, Canadian ice hockey player
• 1984 – Darren Ambrose, English footballer
• 1984 – Adam Sinclair, Indian field hockey player
• 1984 – Cullen Jones, American swimmer
• 1988 – Scott Golbourne, English footballer

Deaths

• 1528 – Patrick Hamilton, Scottish religious reformer (martyred) (b. 1504)
• 1592 – Alessandro Striggio, Italian composer (b. 1540)
• 1604 – John Whitgift, Archbishop of Canterbury (b. 1530)
• 1740 – Pietro Ottoboni, Italian cardinal (b. 1667)
• 1744 – John Theophilus Desaguliers, French philosopher (b. 1683)
• 1820 – Johann Joachim Eschenburg, German literary critic (b. 1743)
• 1868 – Ludwig I of Bavaria (b. 1786)
• 1880 – Sir James Wilson, Premier of Tasmania (b. 1812, also on 29 February)
• 1908 – Pat Garrett, U.S. gunslinger
• 1908 – John Hope, 1st Marquess of Linlithgow, first Governor-General of Australia (as Lord Hopetoun)
• 1928 – Ina Coolbrith, first poet laureate of California (b. 1841)
• 1940 – Edward Frederic Benson, English writer (b. 1867)
• 1944 – Pehr Evind Svinhufvud, President of Finland (b. 1861)
• 1956 – Elpidio Quirino, President of the Philippines (b. 1890)
• 1964 – Frank Albertson, American actor (b. 1909)
• 1968 – Tore Ørjasæter, Norwegian poet (b. 1886)
• 1980 – Gil Elvgren, American artist (b. 1914)
• 1992 – Ruth Pitter, English poet (b. 1897)
• 1992 – Earl Scheib, American car repainter (b. 1908)
• 1996 – Shams Pahlavi, Persian princess (b. 1917)
• 2000 – Dennis Danell, American artist (b. 1961)
• 2004 – Jerome Lawrence, American playwright (b. 1915)
• 2008 – Janet Kagan, American author (b. 1946)

Although the modern calendar counts a year as 365 days, a complete revolution around the sun takes approximately 365 days and 6 hours. Every four years, as an extra 24 hours have accumulated, one extra day is added to keep the count coordinated with the sun's apparent position.

It is however slightly inaccurate to calculate an additional 6 hours each year as the time actually taken for the earth to complete a revolution around the sun is in fact 365 days, 5 hours and 49 minutes. To compensate for the 11 minutes difference, a century year that ends in two zeros is not a leap year unless it is also evenly divisible by 400. This means that 1600 and 2000 were leap years, as will be 2400 and 2800, but 1800 and 1900 were not, and neither will 2100 and 2200 be. To correct the remaining error (which amounts to one day every 3236 years) it has been proposed that years evenly divisible by 4,000 should not be leap years; but this rule has not been officially adopted.

The Gregorian calendar repeats itself every 400 years, which is exactly 20871 weeks including 97 leap days. Over this period February 29 falls 13 times on a Sunday, Tuesday or Thursday; 14 times on a Friday or Saturday; and 15 times on a Monday or Wednesday.

The concepts of the leap year and leap day are distinct from the leap second, which results from changes in the Earth's rotational speed.

The leap day was introduced as part of the Julian reform. The day following the Terminalia (February 23) was doubled, forming the so-called "bis sextum"—literally 'double sixth', since as dates were described in the Roman calendar February 23 was 'the sixth day before the Kalends of March'. The first day of the bis sextum (February 24) came to be regarded as the intercalated or "bissextile" day. February 29 came to be regarded as the leap day when the Roman system of numbering days was replaced by sequential numbering in the late Middle Ages.

An English law of 1256 decreed that in leap years, the leap day and the day before are to be reckoned as one day for the purpose of calculating when a full year has passed. Thus, in England and Wales a person born on February 29 legally reaches the age of 18 or 21 on February 28 of the relevant year. In the European Union, February 29 officially became the leap day only in 2000.

There is a tradition that women may make a proposal of marriage to men only in leap years, further restricted in some cases to only February 29. There is a tradition that in 1288 the Scottish parliament under Queen Margaret legislated that any woman could propose in Leap Year; few parliamentary records of that time exist, and none concern February 29.^[1] Another component of this tradition was that if the man rejects the proposal, he should soften the blow by providing a kiss, one pound currency, and a pair of gloves (some later sources say a silk gown). There were similar notions in France and Switzerland. Generally, these traditions are considered urban legends (see ^[2]).

In France, there is a humorous periodical called La Bougie du Sapeur (The Sapper's Candle) published every February 29 since 1980. The name is a reference to the sapper Camembert.