Who decides how Korean is pronounced?

The National Institute of Korean Language. Standard Korean Pronunciation forms Part 2 of the Standard Language Regulations, and the Romanization of Korean was proclaimed by the Ministry of Culture and Tourism in July 2000.

Why does this site follow the standard rather than how people actually speak?

Because spelling follows the standard, and reading is what a learner needs first. Where everyday speech has drifted — ㅐ and ㅔ, for example — the page for that letter says so explicitly instead of quietly merging them.

Are these translations official?

No. The Korean text is the official wording; the English beside it is our translation, given so you can check what the rule says without reading Korean.

Why is 희 romanized hui when it sounds like [히]?

Because romanization normally follows pronunciation, and ㅢ is the single exception. Note 1 of Chapter 2 Article 1 keeps ui in writing even when the sound is [ㅣ] — the official example is 광희문 Gwanghuimun.

The rules this site follows

Every pronunciation and romanization on this site comes from 8 articles published by the National Institute of Korean Language, and they are all quoted below in the original Korean. Nothing here is our opinion about how Korean sounds — where the standard and everyday speech disagree, we say which is which rather than picking one quietly.

Standard Korean Pronunciation (표준 발음법)

National Institute of Korean Language. Part 2 of the Standard Language Regulations.

Standard Korean Pronunciation, Article 4

'ㅏ ㅐ ㅓ ㅔ ㅗ ㅚ ㅜ ㅟ ㅡ ㅣ'는 단모음(單母音)으로 발음한다.
ㅏ ㅐ ㅓ ㅔ ㅗ ㅚ ㅜ ㅟ ㅡ ㅣ are pronounced as monophthongs.

This is why this site keeps ㅐ and ㅔ apart: the standard lists them as two separate vowels, even though most Seoul speakers now merge them.

Standard Korean Pronunciation, Article 4, Note

[붙임] 'ㅚ, ㅟ'는 이중 모음으로 발음할 수 있다.
[Note] ㅚ and ㅟ may also be pronounced as diphthongs.

Gives every ㅚ syllable a second, permitted reading — 괴 is [괴] or [궤].

Standard Korean Pronunciation, Article 5, Proviso 1

용언의 활용형에 나타나는 '져, 쪄, 쳐'는 [저, 쩌, 처]로 발음한다.
져, 쪄 and 쳐 appearing in conjugated verb forms are pronounced [저], [쩌] and [처].

After ㅈ, ㅉ and ㅊ the y-glide is not realised, so 쟈 is read [자] and 져 is read [저]. Those consonants are already palatal, and the glide is absorbed.

Standard Korean Pronunciation, Article 5, Proviso 2

'예, 례' 이외의 'ㅖ'는 [ㅔ]로도 발음한다.
Apart from 예 and 례, ㅖ may also be pronounced [ㅔ].

Gives 계, 폐 and the rest a second permitted reading — [계] or [게]. 예 and 례 are excluded and keep one reading.

Standard Korean Pronunciation, Article 5, Proviso 3

자음을 첫소리로 가지고 있는 음절의 'ㅢ'는 [ㅣ]로 발음한다.
In a syllable that has a consonant as its initial sound, ㅢ is pronounced [ㅣ].

희 is read [히] and 긔 is read [기]. Only 의 keeps the full ㅢ sound, because ㅇ carries no sound in initial position.

Standard Korean Pronunciation, Article 9

받침 'ㄲ, ㅋ', 'ㅅ, ㅆ, ㅈ, ㅊ, ㅌ', 'ㅍ'은 어말 또는 자음 앞에서 각각 대표음 [ㄱ, ㄷ, ㅂ]으로 발음한다.
At the end of a word or before a consonant, the finals ㄲ ㅋ / ㅅ ㅆ ㅈ ㅊ ㅌ / ㅍ are pronounced as their representative sounds [ㄱ], [ㄷ] and [ㅂ].

This is why a letter can sound different at the end of a syllable than at the start — ㅅ is s in 사 but t at the end of 옷.

Romanization of Korean (국어의 로마자 표기법)

Ministry of Culture and Tourism. Proclamation No. 2000-8, 7 July 2000.

Romanization of Korean, Chapter 1, Article 1

국어의 로마자 표기는 국어의 표준 발음법에 따라 적는 것을 원칙으로 한다.
Korean is romanized in accordance with standard Korean pronunciation.

Romanization follows the sound, not the spelling — which is why 져 is written jeo and not jyeo.

Romanization of Korean, Chapter 2, Article 1, Note 1

'ㅢ'는 'ㅣ'로 소리 나더라도 'ui'로 적는다. (광희문 Gwanghuimun)
ㅢ is written ui even when it is pronounced [ㅣ]. (광희문 Gwanghuimun)

The single place where the pronunciation line and the romanization line disagree: 희 sounds like [히] but is written hui.

What we deliberately leave out

Many learners are told that ㅐ and ㅔ, ㅒ and ㅖ, or ㅙ ㅚ and ㅞ are simply the same sound. In everyday Seoul speech that is largely true, and each letter's page says so. But the standard defines them as separate vowels, and the spelling difference still separates real words — 개 is a dog and 게 is a crab. Merging them in a reference table would teach the wrong spelling, so this site keeps them apart and explains the gap instead.

Questions people ask

Who decides how Korean is pronounced?: The National Institute of Korean Language. Standard Korean Pronunciation forms Part 2 of the Standard Language Regulations, and the Romanization of Korean was proclaimed by the Ministry of Culture and Tourism in July 2000.
Why does this site follow the standard rather than how people actually speak?: Because spelling follows the standard, and reading is what a learner needs first. Where everyday speech has drifted — ㅐ and ㅔ, for example — the page for that letter says so explicitly instead of quietly merging them.
Are these translations official?: No. The Korean text is the official wording; the English beside it is our translation, given so you can check what the rule says without reading Korean.
Why is 희 romanized hui when it sounds like [히]?: Because romanization normally follows pronunciation, and ㅢ is the single exception. Note 1 of Chapter 2 Article 1 keeps ui in writing even when the sound is [ㅣ] — the official example is 광희문 Gwanghuimun.