The Four Tone Marks ่ ้ ๊ ๋

Thai has four written tone marks: ่ ไม้เอก, ้ ไม้โท, ๊ ไม้ตรี, and ๋ ไม้จัตวา. They are combining marks placed above the onset area of a syllable. They do not represent consonants or vowels, and none has one fixed spoken pitch independent of its context.

The mark selects an outcome through the consonant class. On a live syllable, ่ gives a low tone with a mid- or high-class initial but a falling tone with a low-class initial. The historical class system is therefore not redundant baggage: it is part of the instructions that make the same visible mark readable.

Names, Unicode identity, and position

The marks are encoded after the consonant and after any upper vowel that occupies the same vertical stack. For กี่, the logical sequence is ก + ี + ่, and the font places ่ above ี. In a true onset cluster, the mark is conventionally positioned over the second consonant, as in กล้า. In ห นำ, it likewise appears over the pronounced low consonant, as in ใหม่, even though leading ห supplies high-class behavior.

The class-dependent map for live syllables

The following table deliberately uses live syllables. Unmarked dead syllables require additional rules, including a vowel-length split for low-class initials, and belong on tone-rule inputs.

The traditional names เอก, โท, ตรี, and จัตวา number the marks; they are not universal names for the resulting modern pitches. Thai traditional tone labels use the same words in another related system, which makes careless English explanations particularly misleading.

Mid class displays all five tones

The ปา series holds the onset and long live vowel constant while varying only the mark:

RTGS renders every one as pa. That is not a typographical oversight: the system omits both tone and vowel length. Only the Thai line identifies which word is meant.

Mid-class initials are the regular home of all four written marks. ไม้ตรี and ไม้จัตวา also appear prominently in loanwords, expressive vocabulary, and colloquial kin terms, but the marks themselves are not inherently informal. โต๊ะ to “table,” a loanword with ๊, is neutral everyday vocabulary.

The same mark, different result

Compare high-class ข and paired low-class ค. Both have initial kh in RTGS, yet class changes the result of each mark.

The pronoun ข้า is (literary, historical, or role-dependent) rather than a neutral everyday “I.” Its value in the table is phonological; learners should not adopt it as their default pronoun.

A mark can stack above a vowel

Walk through กี่ ki “how many”:

1. ก is the mid-class onset.
2. ี is the long vowel written above ก.
3. ่ is encoded after ี and displayed above it.
4. The open long syllable is live.
5. Mid class + live + ่ gives a low tone.

Now consider ซื้อ sue “buy.” The vowel uses ื above ซ and อ after it; ้ stacks above ื. Low-class ซ plus ้ gives a high tone.

The vertical stack is not pronunciation order. Read the onset first, assemble the surrounding vowel, identify the tone mark, and only then apply the class rule.

Clusters and leading consonants

In กล้า kla “dare/brave,” the onset is the true cluster กล. The mark is written over ล, but mid-class ก controls the cluster’s tone pattern.

In ใหม่ mai “new,” the mark appears over ม. The initial sound is /m/, but leading ห makes the syllable follow high-class behavior. High-class live + ่ gives a low tone.

These spellings prove that “look directly under the mark” is not a sufficient tone algorithm.

Unmarked syllables still have tones

Most Thai syllables do not need a written tone mark. Class and syllable structure can already predict a lexical tone. In the live, unmarked set, กา is mid, ขา is rising, and คา is mid. In dead syllables the coda and, for some low-class cases, vowel length change the outcome.

Several syllables here lack marks but do not share one tone. RTGS suppresses all the tone contrasts, so it cannot replace the native calculation.

A real sign: ห้ามเข้า

Both ห้าม and เข้า begin with high-class consonants and carry ้. ห้าม is live because final ม is /m/; เข้า is live because the เ–า rime ends in a /w/ glide. High class + live + ้ gives a falling tone in both. In เข้า, preposed เ appears before ข visually; the spoken onset and class still come from ข.

Common Mistakes

1. Giving each mark one invariant tone.

2. Assuming no mark means mid tone.

3. Typing a cluster’s tone mark over the wrong consonant.

4. Ignoring vowel length because RTGS omits it.

Key Takeaways

The marks ่ ้ ๊ ๋ are combining characters and class-dependent tone inputs. They stack above the onset area, including above an upper vowel or the second consonant of a cluster. Mid class uses the complete four-mark set regularly; high and low classes use complementary rows dominated by ่ and ้. Unmarked syllables still have lexical tones, and neither a visible mark nor RTGS can replace the full calculation from class, syllable type, vowel length, and spelling structure.