A Thai syllable can end in only eight sounds.
You met the consonants as syllable starts, where all 44 are different. At the end of a syllable they do a much smaller job: whatever is written, only these eight endings ever come out.
Three cut the voice off
e.g.
มาก
a lot
e.g.
ผิด
wrong
e.g.
จบ
to finish
Five let the voice run on
e.g.
ห้อง
room
e.g.
กิน
to eat
e.g.
ถาม
to ask
e.g.
ร้อย
hundred
e.g.
เร็ว
fast
Many different letters write the same ending.
This is the part that looks harder than it is. Fifteen letters all end a syllable with the same -t sound. You do not learn fifteen endings — you learn one, and recognise the letters that write it.
ผิด
ends in ด-twrong
รถ
ends in ถ-tcar
พูด
ends in ด-tto speak
ตำรวจ
ends in จ-tpolice
ประเทศ
ends in ศ-tcountry
The same collapse happens with -k (four letters), -p (five) and -n (five). The other four endings are written one way each.
What this buys you
That split — voice cut off versus voice running on — has a name. A syllable ending in a stop is called dead; one ending in a sonorant is live. So reading the last letter already tells you which it is, without knowing the word:
ปาก
ก = -kdeadmouth
งาน
น = -nlivework
ภาพ
พ = -pdeadpicture
ข้าว
ว = -wliverice
Live or dead is one of the three things that decide a syllable’s tone, alongside the consonant class you already know and the tone mark. Those rules come next — this was the piece they were missing.
No final consonant? The vowel decides.
A syllable that ends in a long vowel is live — the voice continues, nothing stops it. One that ends in a short vowel is dead — it stops abruptly, as if there were a final stop. Here is one frame, ended eight ways:
Live syllables (คำเป็น)
End in a long vowel, or a sonorant (-ng, -n, -m, -w, -y). Voice continues — nothing stops it.
กา
long vowel → liveกาน
ends in -n → liveกาง
ends in -ng → liveกาว
ends in -w glide → liveDead syllables (คำตาย)
End in a short vowel (abrupt), or a stopped consonant (-k, -t, -p). Voice is cut off.
กะ
short vowel → deadกาก
ends in -k → deadกาด
ends in -t → deadกาบ
ends in -p → deadQuick test
Does the syllable end in -k, -t, -p, or an abrupt short vowel? → Dead. Otherwise → Live. This single binary immediately halves the tone possibilities.