Greetings

How do you say thank you in Thai?

ขอบคุณครับ / ขอบคุณค่ะ: khob khun khrap (men) / khob khun kha (women). After "hello," this is the second most useful phrase in the language. Pairing it with a small wai makes it land even better.

Thanks, and what comes back

Four phrases from Thailo's phrasebook, covering how to thank someone, how they'll likely respond, and the all-purpose apology that does double duty:

Male or female: it's the particle that changes

The word for thanks, khob khun, never changes. What changes is the little politeness particle on the end, and it follows your gender, not the person you're thanking. A man says khob khun khrap; a woman says khob khun kha. That's the whole rule, and it's the same particle you'll attach to almost every polite sentence in Thai. More on that in khrap vs. kha.

khob khun, kapunka, kop khun: why the spelling keeps changing

Thai has no single official romanization, so the same phrase gets written a dozen ways in the wild. You'll run into khop khun, kop khun, kob khun, khab khun, and the run-together kapunka or kapunkap on menus and thank-you signs. Those last two aren't a different phrase; they're the whole thing said at speed: kapunka is khob khun kha (a woman), kapunkap is khob khun khrap (a man). Once you've heard it, every spelling snaps to the same sound.

The phrase you'll hear back

Say khob khun khrap/kha and you'll often hear mai pen rai in response: Thailand's all-purpose "you're welcome / no worries / it's fine." It's worth recognizing even before you can say it yourself, since you'll hear it constantly. Paired with sawasdee, it covers most of the small talk a visitor ever needs.