I’ve read different things. Can you use a 2 round prong European adapter with US curling iron or iPad, etc. in Bangkok or Chaing Mai?

Thailand voltage is 220 or 230 volts AC. USA uses 120V. The plugs are ok according to google but the devices need to be "dual voltage".

Apple chargers are 100-240 VAC so your ipad is ok. It says so on the thing. For the curler the requirements are probably printed on the body/handle or on a tag attached to the power cord. For a laptop you probably have a cord going from the plug into a "brick" and another cable going from the brick into the laptop. That brick is the voltage converter and it will have the voltage rating printed on it. Other electrical things have bricks

This the google stuff:

Electrical sockets in Thailand are compatible with both flat parallel prongs (like in the United States and Japan) and two round pins (like in most European and Asian countries). While two-pin sockets are common in Thailand, some establishments like hotels and offices also have three-pin outlets installed.

What plug sockets are used in Thailand? For Thailand there are four associated plug types, types A, B and C. Plug type A is the plug which has two flat parallel pins, plug type B has two flat parallel pins and a grounding pin and plug type C has two round pins. Thailand operates on a 230V supply voltage and 50Hz.

Ok, my laptop plug is type B: two flat prongs and a round one as ground. So, an adapter would be a good thing to have. There are universal plug adapters for ten bucks.

The 2-round prong European adapter is type C. You won't need it if the socket is type B. You can plug type A (two pin, like your ipad charger) into type B socket. In addition to that euro adapter you might want a B to A adapter (i.e. USA 3-prong to 2)

Thank you. What had me confused was on a search that said I would need a type O plug.

Take your euro adapter type C. The type O plug looks like a C plug with a ground.

Type O is used only in Thailand. outlet compatible with types C and O plugs (partial compatibility with types E and F – danger!)

The Type O Plug & Socket is grounded, has an amp rating of 16 A, voltage range of 220-240 V, and is compatible with plug types C and O. It is unsafely partially compatible with plug types E and F.

https://www.worldstandards.eu/electr...and-sockets/o/
For now, type O outlets only exist on paper. All sockets that are currently sold are hybrid ones, which are compatible with types plug types A, B, C and O.

Itb occurs to me that your "2 round prong European adapter" might accept both US plug types, the B-grounded and he A ungrounded. If so then no need for B to A adapter. The sockets are hybrid anyway.

Worst case is you need an adapter that your hotel can't give you and you have to go out shopping for one with straight hair.

“Go out shopping for one with straight hair”. LOL

I guess I’m on vacation so who cares?

Actually, as long as I can charge my iPhone, iPad, and my Fitbit watch, I don’t care about my hair….we’ll maybe!

International power adapters are easy to find in Southeast Asia. I paid about $2.50 USD for mine at a local market. Most Thai outlets can handle US style two or three-prong plugs. Often the room A/C unit has a Type O outlet exclusively for A/C use. Strongly recommended not to bring any 120 V only appliances to Southeast Asia, particularly a resistance heating appliance like a hair curler. If it is not fused properly, it may catch fire from the higher voltage forcing 4x the wattage through the device.

All depends on where you are staying! Higher end places have universal outlets, cheaper places do not! My opinion is to go on Amazon, and spend $20 on a really go converted, and never have to worry about it. Don't buy one in the airport, they are super expensive and not the best.