Traditionally the Korean language contains 10 pure vowels that can still be heard in the speech of some speakers today: /a, ɛ, ʌ, e, o, ø, u, y, ɯ, i/. The Korean phonetic system distinguishes between 7 monophthongs, or pure vowels. So while both languages share many sounds in common, the phonetic notations in Vocaloid can differ somewhat. Since Japanese only includes one glide /j/, it is always written in the onset of a syllable as a palatalized consonant, rather than as part of the vowel. However the vowel may include a glide, which causes another major difference between Korean's system and Japanese. Korean syllables are traditionally separated into three parts: CVC (Consonant-Vowel-Consonant). This can cause confusion for users as the similar transcriptions for consonant phonemes in Korean do not match the sounds in other languages. As a result, Korean does not distinguish between unvoiced and voiced rather, both are allophones of a single phoneme /k/. Unlike English and Japanese which classifies stop consonants based on voiced and unvoiced pairs, Korean distinguishes between three sets of initial stop consonants plain, tense and aspirated. This is somewhat due to the nature of hangul, which already functions as a phonetic alphabet.

The phonetic system for Korean Vocaloids uses less standard transcription compared to the typical notation used by other languages that are based on X-SAMPA. The following are a list of Vocaloids that use Korean.