Below, you'll find some Thai phrases that may come in handy when you are travelling in Thailand. But first...
A Brief Note on Polite Particles
Most of these phrases can (and should) be made more polite by adding a
particle to the end. Male speakers
should add
¤ÃѺ 
/khrap
H/ while women should add
¤èÐ 
/kha
F/ to the end of statements and
¤Ð 
/kha
H/ to the end of
questions.
¨éÐ /ja
F/ can be used by children or between intimate friends. There are many more particles
in common use, especially considering regional variations; some Thai people will stick with an obscure
favorite as a matter of personality.
At first, Westerners find these particles easy to forget, but with practice, eventually you will find yourself
adding polite particles automatically. You can further "soften" requests or aggresive statements by also adding
¹èÐ /na
F/ before you say khrap
H or kha
F (ladies, remember to use
¹èÐ /na
F/
¤Ð 
/kha
H/ to make your questions more polite).
If you listen to broadcast talk shows in Thailand, you may hear a speaker ending every single sentence with
/na
F khrap
H/—since he doesn't know who may be listening, he endeavors to be most polite.
ÊÇÑÊ´Õ  | saL watL deeM | [a polite greeting or farewell used when meeting or parting] hello; goodbye; good morning; good afternoon; good evening; good night; greetings |
ʺÒ´ÕËÃ×Í  | saL baayM deeM reuuR | "How are you?" |
¢Íº¤Ø³  | khaawpL khoonM | [spoken formally to a person of higher rank or status, e.g. parents, teachers] "Thank you" [male: add ¤ÃѺ ; female: add ¤èÐ ] |
¹Õèà·èÒäÃ?  | neeF thaoF raiM | "How much is this?" |
äÁèà»ç¹äÃ  | maiF bpenM raiM | "It doesn't matter." — "Never mind." — "You're welcome" — "Don't mention it." — "It's no big deal." |
áÅéǾº¡Ñ¹ãËÁè  | laaeoH phohpH ganM maiL | "See you later." — "See you soon!" — "Until we meet again." |
¢Íâ·É  | khaawR thohtF | "I apologize" — "I'm sorry" — "Excuse me" — "Pardon me." |
ʺÒ´Õ  | saL baayM deeM | to be feeling fine; I am fine; I'm fine. |
ÊÇÑÊ´Õ¤ÃѺ  | saL watL deeM khrapH | [spoken politely by a male] hello; goodbye |
ÊÇÑÊ´Õ¤èÐ  | saL watL deeM khaF | [spoken politely by a female] hello or goodbye |
¾Ù´ä·ÂäÁèä´é  | phuutF thaiM maiF daiF | "I can't speak Thai." |
äÁèà¢éÒã¨  | maiF khaoF jaiM | (I) don't understand |
à¢éÒã¨äËÁ  | khaoF jaiM maiR | Do you understand? |
¶èÒÂÃÙ»ä´éäËÁ  | thaayL ruupF daiF maiR | May I take a picture? |
Ëéͧ¹éÓÍÂÙè·Õèä˹  | haawngF naahmH yuuL theeF naiR | Where's the restroom? |
¹ÕèÍÐäÃ  | neeF aL raiM | "What is this?" |
á¾§äËÁ?  | phaaengM maiR | Is it expensive? |
¢ÍãËé⪤´Õ  | khaawR haiF chohkF deeM | "Good luck to you." |
ã¤Ã¢ÒÂä¢èä¡è  | khraiM khaayR khaiL gaiL | [tongue twister, alliteration] "Who sells chicken eggs?" |
à¡çºµÑ§¤ì  | gepL dtang[k]M | "Check, please." |
à»ç¹Âѧ䧺éÒ§?  | bpenM yangM ngaiM baangF | "How's it going?" — "How do you feel?" — "How do you do?" — "What's up?" |
¤Ø³ÍÒÂØà·èÒäÃ  | khoonM aaM yooH thaoF raiM | "How old are you?" |
ÍÐäáçä´é  | aL raiM gawF daiF | anything will do; that option would also be fine; whatever; anything will be okay |
ä»ä˹  | bpaiM naiR | Where are you going? |
¤Ø³¾Ù´ÀÒÉÒÍѧ¡ÄÉä´éäËÁ  | khoonM phuutF phaaM saaR angM gritL daiF maiR | "Can you speak English?" |
¢Íº¤Ø³ÁÒ¡  | khaawpL khoonM maakF | [a person, younger and/or lower in status, thanking the other who is older and/or higher in status] "Thank you very much" |
¢ÍäÁèà¼ç´  | khaawR maiF phetL | "Please make the food not spicy-hot." |
¢Íà¼ç´ æ ¹Ð¤ÃѺ  | khaawR phetL phetL naH khrapH | [spoken by a male] "Please make the food spicy-hot" |
¡ÃسҾٴªéÒ æ ˹èÍÂ  | gaL rooH naaM phuutF chaaH chaaH naawyL | "Please speak slowly." |
ÍÐäùÐ?  | aL raiM naH | "What?" — "Huh?" — "What did you say?" — "What was that?" |
¤Ø³ÍÂÙè·Õèä˹  | khoonM yuuL theeF naiR | "Where are you?" |
äÁèãªè  | maiF chaiF | "I don't think so" — "not right" — "not so" — "not true" — "No, it is not" |
¤Ø³à»ç¹¼ÙéªÒÂËÃ×ͼÙéËÔ§  | khoonM bpenM phuuF chaayM reuuR phuuF yingR | "Are you a man or a woman?" |
¡ÕèâÁ§áÅéÇ  | geeL mohngM laaeoH | "What time is it?" |
¼ÁäÁèà¢éÒã¨  | phohmR maiF khaoF jaiM | "I don't understand." — "I do not understand." |
¼Áà»ç¹¤¹ÍàÁÃԡѹ  | phohmR bpenM khohnM aL maehM riH ganM | "I am an American." |