Greetings and politeness (สวัสดี)

One Greeting, All Day

Thai has a single all-purpose greeting: สวัสดี (sà-wàt-dii). It works in the morning, in the evening, arriving AND leaving — there is no good morning / good night split to learn. Follow it with your politeness particle:

speakergreeting
a manสวัสดีครับ
a womanสวัสดีค่ะ

The usual follow-up is the question you can already build: สบายดีไหมare you well? — answered by echoing the verb: สบายดี (I'm well).

Thank You and the Reply

ขอบคุณ (khɔ̀ɔp-khun) is thank you. Strengthen it with มาก: ขอบคุณมาก — thank you very much.

The standard reply is ไม่เป็นไร (mây-pen-ray) — literally it is nothing. It does triple duty: you're welcome, never mind, and it's okay after an apology. It is one of the most Thai sentences there is — learn it as a single unit.

Thank you very much. (male speaker)
ขอบคุณ มาก ครับ

Sorry — and Excuse Me

ขอโทษ (khɔ̌ɔ-thôot) covers both sorry (an apology) and excuse me (getting someone's attention before a question). The reply to an apology is the same ไม่เป็นไร.

Leaving

ลาก่อน (laa-kɔ̀ɔn) is the plain goodbye — a touch formal, for real partings. Between friends who will meet again, แล้วเจอกัน (lɛ́ɛw-cəə-kan) — see you later — is the everyday choice. And สวัสดี itself works on the way out too.

Contributors