Hangeul's Origin: King Sejong, 28 Letters, and Hangeul Day

Hangeul, the Korean alphabet, was completed by King Sejong the Great in the twelfth lunar month of 1443 and published in the ninth lunar month of 1446. It started with 28 letters. Today's alphabet uses 24, because four of the original letters were dropped. Korea marks the publication every year on October 9, Hangeul Day, which is listed as a public holiday for 2026.

1. Why a new alphabet was needed

According to the Korea Heritage Service, Sejong was the fourth king of the Joseon Dynasty and reigned from 1418 to 1450. Koreans of his time wrote with Chinese characters. Sejong's concern, as the Service describes it, was that those characters were built to represent Chinese, a language with a completely different structure from Korean, so they were hard for Koreans to learn and use.

The solution was a writing system designed for Korean sounds. Sejong named it Hunminjeongeum, usually translated as "Proper Sounds for the Instruction of the People." The word "Hangeul" is newer. The Service says the name, combining han (meaning the Korean people, or "great") and geul (letters), was given to the script early in the 20th century.

2. The 28 letters, and the 24 used now

The National Hangeul Museum counts the original set as 28 letters: 17 consonants and 11 vowels. Two design ideas are worth knowing.

• Consonants copy the shape of the speech organs used to make the sound. The museum describes the form of each consonant as reflecting the vocal organs when that letter is pronounced.
• Vowels are built from three basic marks that stand for the three elements of the universe in Neo-Confucian thought: sky, earth, and humanity.

Letters are then stacked into syllable blocks, and the museum notes that this makes it possible to write any sound in Korean. The Korea Heritage Service adds that today's Hangeul uses only 24 of the original 28 letters, and that the system is easy to learn and use. The arithmetic is simple: 28 minus the 4 dropped letters leaves 24.

3. From 1443 to 1446: the two dates

People often quote 1443 and 1446 as if they conflict. They mark two different events.

The book had two parts. The first was the main text written by Sejong himself, with a preface explaining why he created the letters, followed by explanations of the 28 letters and how they combine into syllables. The second was a set of commentaries by scholars of the Jiphyeonjeon ("Hall of Worthies") written on his order. The Service describes six chapters in all, covering the design of the letters, initial consonants, vowels, final consonants, combining letters, and examples of use. The whole text is only 33 leaves: 4 leaves of main text plus 29 of commentary.

4. Why October 9 is Hangeul Day

The exact day of publication is not recorded. The Annals of King Sejong say only that the book appeared in the ninth lunar month of 1446. A postface by the scholar Jeong In-ji, included in the book, was written in the first ten days of that month. From that, the Service reasons the book was published by the tenth day, and that date converts to October 9 on the solar calendar. October 9 was designated Hangeul Day, a national holiday.

For 2026, the Korea Tourism Organization lists Hangeul Day (October 9) among Korea's 14 public holidays, describing it as a commemoration of the creation of Hangeul as proclaimed by the publication of Hunminjeongeum in 1446 (as of October 2026).

5. The copy that was nearly lost

The previously known editions lacked the scholars' explanations. The complete one, called the Haerye Edition, includes them. The Service says it was thought to have been long lost, but a copy turned up by chance in 1940 in an old house in Andong, in Gyeongsangbuk-do. It is now kept at the Kansong Art Museum in Seoul, and the government designated it a national treasure in 1958. The Service's page sits in its Memory of the World section, and it describes the book as a legacy of world culture.

6. Who learned it at home

The National Folk Museum of Korea notes that in the Joseon Dynasty, men studied at village schools and then at public schools or private academies to prepare for state exams, while women learned Hangeul at home and used it to exchange letters and read books translated into Korean.

7. Key takeaways

• Sejong completed the alphabet in the twelfth lunar month of 1443 and it was published in the ninth lunar month of 1446.
• The original 28 letters (17 consonants, 11 vowels) became 24 in modern use.
• Consonant shapes reflect speech organs; vowels come from sky, earth, and humanity marks.
• October 9 is a calculated date: publication by the tenth day of the ninth lunar month, converted to the solar calendar.
• A complete Haerye Edition copy was found in 1940 and became a national treasure in 1958.