Ordering is the first thing most people use Thai for and the fastest place to see a return on it. Staff at street stalls and small shops often speak little English, and the gap between pointing at a photo and saying one sentence is larger than you would expect.
Start with the spice section below if you are short of time. It is the phrase that saves the most suffering.
Asking for something
Two verbs cover most of it. เอา is closer to "I'll have" and is what you use for food. ขอ is "may I have" and is slightly softer, used for requests and small things.
Spice level
Thai "not spicy" is still warmer than most Western palates expect. Saying it at all makes a real difference, and nobody will think less of you for it.
The one to learn first.
Dishes worth knowing by name
Ordering by name rather than by pointing changes how the exchange goes, and these five cover most stalls.
What is in it
Drinks and ice
Ice in Thailand is made commercially and is generally fine. If you would still rather not, this is how to say so.
Paying and leaving
Worth saying on the way out. It lands well.
One pattern does most of the work
Nearly everything above is the same shape. เอา plus a dish, then any changes on the end.
เอา___ไม่เผ็ด
ao ___ mai pet
"I'll have ___, not spicy."
Swap the dish and you have as many sentences as you have dish names. Thai has no conjugation and no agreement, so the slot genuinely just swaps. Learning five patterns like this one will take you further than learning fifty separate phrases.
Add ครับ if you are male or ค่ะ if you are female to the end of anything and it becomes polite. Leaving it off is not rude exactly, but it is noticeably blunt, and using it is the single cheapest way to sound like someone who has bothered.
Common questions
How do you say "not spicy" in Thai?
Mai pet, written ไม่เผ็ด. Add krap if you are male or ka if you are female to make it polite. Be aware that Thai "not spicy" is often still warmer than what most visitors expect.
How do you order food in Thai?
Use ao (เอา) followed by the dish name, then any changes. So "ao pat ga-prao mai pet" means "I will have pad kra pao, not spicy". Finish with krap or ka to be polite.
Do I need to speak Thai to eat at street stalls?
No, pointing works. But a handful of phrases changes the exchange noticeably, and at smaller stalls away from tourist areas there may be no English and no pictures to point at.
What does krap or ka mean?
They are politeness particles added to the end of a sentence. Men say krap, women say ka. They carry no meaning of their own, and leaving them off makes you sound blunt rather than rude.