How is a Hangul syllable block built?

A Korean syllable block has up to three parts: a leading consonant (choseong), a medial vowel (jungseong), and an optional final consonant (jongseong). They are arranged into a single square block, not written linearly, which is what gives Hangul its distinctive look.

How does Unicode compose the block?

Unicode places all 11,172 modern syllables in one ordered range starting at U+AC00. The formula is code = 0xAC00 + (initial × 21 + medial) × 28 + final, where initial is 0 to 18, medial is 0 to 20, and final is 0 to 27 (0 meaning no final consonant).

Why are there exactly 11,172 syllables?

There are 19 possible initials, 21 possible medials, and 28 final slots (27 consonants plus the empty slot). Multiplying 19 × 21 × 28 gives 11,172, which is the count of precomposed modern Hangul syllable blocks in Unicode.

What is the difference between a jamo and a syllable block?

A jamo is a single Hangul letter — a consonant or vowel — while a syllable block is the composed square made of two or three jamo. The standalone jamo at U+3131 onward look slightly different from the same letters inside a block.

Is anything sent to a server?

No. The composition is pure arithmetic done in your browser using the Unicode formula. Nothing you select is uploaded.

Korean Syllable Block Builder

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Korean is written in Hangul, where letters are not strung out in a line but packed into square syllable blocks. Each block has up to three parts: a leading consonant (choseong), a medial vowel (jungseong), and an optional final consonant (jongseong). This builder lets you pick each part and instantly composes the exact precomposed Unicode syllable, showing its code point — a clean way to see how Hangul’s elegant composition system works.

How it works

Unicode stores all 11,172 modern Hangul syllables in one contiguous, ordered range beginning at U+AC00 (가). Any block is computed with a single formula:

code = 0xAC00 + (initial × 21 + medial) × 28 + final

where:

initial is the choseong index, 0–18 (19 consonants).
medial is the jungseong index, 0–20 (21 vowels).
final is the jongseong index, 0–27 — index 0 means no final consonant, and 1–27 are the final consonants.

Multiplying the slot counts gives 19 × 21 × 28 = 11,172 syllables, exactly the size of the Unicode block. The arithmetic means every selection maps to one unambiguous character.

Example and notes

To build 한 (han): the initial ㅎ has index 18, the vowel ㅏ has index 0, and the final ㄴ has index 4. Plug in: 0xAC00 + (18 × 21 + 0) × 28 + 4 = 0xD55C. Leave the final on “(none)” and you get 하 (ha) instead. Standalone jamo letters (ㅎ, ㅏ) look slightly different from their in-block forms — the builder always outputs the composed block, not the loose jamo.