What is a 받침 and why does it matter?

A 받침 (batchim) is a final consonant at the bottom of a Korean syllable block. Many particles have two forms, and the choice between them depends entirely on whether the preceding noun ends in a batchim (consonant) or in a vowel. Picking the wrong alternant sounds clearly ungrammatical.

What is the difference between 은/는 and 이/가?

은/는 is the topic marker, framing what the sentence is about and often implying contrast, while 이/가 is the subject marker that identifies the doer, frequently with new information. The two-form split within each pair is purely phonological: 은 and 이 follow consonants, 는 and 가 follow vowels.

How do I choose between 을 and 를?

을 and 를 both mark the direct object. Use 을 after a noun ending in a consonant and 를 after a noun ending in a vowel. For example 밥을 (rice + object) but 사과를 (apple + object). The rule is the same consonant-versus-vowel test used by the other paired particles.

Does 으로/로 follow the same rule?

Almost. 으로 attaches to consonant-final nouns and 로 to vowel-final nouns, but there is one exception: nouns ending in the consonant ㄹ (rieul) take 로, not 으로. So 손으로 (with the hand) but 칼로 (with a knife), because 칼 ends in ㄹ.

Are all Korean particles paired?

No. Some particles such as 의 (possessive), 에 (location/time), 에서 (from/at), 도 (also), and 부터/까지 (from/until) have a single form regardless of the preceding sound. Only a handful of high-frequency particles have the consonant/vowel alternation, but those are the ones learners use constantly.

What is the Korean Particle (조사) Reference?

Lists the major Korean postpositional particles with their grammatical role and the consonant-final versus vowel-final alternant (은/는, 이/가, 을/를, 와/과, 으로/로), and picks the correct form for any Korean noun you enter. It runs free in your browser on Gera Tools, with nothing uploaded.

Korean Particle (조사) Reference

Name: Korean Particle (조사) Reference
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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Korean attaches particles (조사, josa) after nouns to mark their grammatical role. Several of the most common particles come in two forms, and which one you use depends on whether the noun ends in a consonant (a 받침, batchim) or a vowel. This tool explains each particle and automatically picks the right alternant for any Hangul noun you type.

How it works

The rule is phonological. For each paired particle:

noun ends in a consonant (받침)  →  use the "consonant" form
noun ends in a vowel             →  use the "vowel" form

The major pairs:

은 / 는     topic marker        (책은 / 사과는)
이 / 가     subject marker      (책이 / 사과가)
을 / 를     object marker       (책을 / 사과를)
와 / 과     "and / with"        consonant→과, vowel→와
으로 / 로   "by / to / with"    + exception: ㄹ-final takes 로

To detect a 받침, the tool decomposes the last Hangul syllable: each modern syllable block is computed as 0xAC00 + (initial × 588) + (medial × 28) + final. If the final index is non-zero the syllable ends in a consonant. The particle 으로/로 adds one twist — a noun ending in ㄹ takes 로, not 으로.

Particle reference table

Particle	Role	After consonant	After vowel	Example (consonant)	Example (vowel)
은/는	Topic marker	은	는	책은	사과는
이/가	Subject marker	이	가	책이	사과가
을/를	Object marker	을	를	책을	사과를
와/과	”And / with”	과	와	밥과	커피와
으로/로	Direction, instrument, by means of	으로 (except ㄹ→로)	로	손으로	버스로

Single-form particles (no alternation)

These attach the same way regardless of the final sound:

의 — possessive marker (나의 = my)
에 — location or time (학교에 = at school / at school-time)
에서 — location of action, or origin (서울에서 = in Seoul / from Seoul)
도 — “also, even” (나도 = me too)
만 — “only” (한 개만 = only one)
부터 — “from, starting from” (월요일부터 = starting from Monday)
까지 — “until, up to” (금요일까지 = until Friday)

The 으로/로 exception — ㄹ-final nouns

The instrumental/directional particle 으로/로 has a special rule that trips up learners: nouns ending in the consonant ㄹ take 로, not 으로, even though ㄹ is a consonant. This is because ㄹ is liquid and phonologically behaves closer to a vowel-final environment in this context.

For example:

손 (hand, ends in ㄴ) → 손으로 (by hand / with the hand)
칼 (knife, ends in ㄹ) → 칼로 (with a knife) — not 칼으로
버스 (bus, ends in vowel ㅡ) → 버스로 (by bus)

Why topic versus subject marker matters

The 은/는 and 이/가 distinction is one of the trickiest in Korean grammar. Both mark the “doer” of the sentence, but:

이/가 (subject marker) highlights new information or identifies who does something for the first time. “Who ate the cake? 제가 먹었어요.”
은/는 (topic marker) marks known information or contrast. “As for me, I ate it (but my brother did not).” 저는 먹었어요.

Type a Korean noun into the tool to see which form of each particle to attach and why, based on the final-sound rule. Everything runs locally in your browser.