Should I buy an eSim online instead?

Buying an eSim (like Airalo) before you land is more convenient as you'll have data the second you step off the plane. However, physical SIMs at the airport are cheaper and offer more data for the price.

Can I top up my credit later?

Yes. If your data runs out, you can buy top-up vouchers at any 7-Eleven store across Thailand. Just give the clerk your phone number and the amount you want to add.

Buying a SIM Card in Thailand as a Tourist

Buy your SIM card directly at the official carrier kiosks inside Suvarnabhumi (BKK) or Don Mueang (DMK) airports immediately after clearing customs. It takes about 10 minutes, and the staff will handle the entire activation process for you.

Choose your carrier. There are three main providers: AIS, DTAC, and TrueMove. AIS generally has the best nationwide coverage, especially if you plan on visiting rural islands or northern mountains.
Bring your passport. Thai law requires all SIM cards to be registered to a name. You must present your physical passport at the counter; they will take a photo of it to register the SIM to your identity.
Select a tourist plan. Ask for a 'Tourist SIM.' These come in 8, 15, or 30-day packages with unlimited (though speed-capped after a certain data limit) internet. Don't bother with regular local plans, as they require a work permit or long-term visa.
Verify activation. Hand your phone to the attendant. They will swap the card, set the APN settings, and ensure you have a data connection before you walk away from the counter.

Should I buy an eSim online instead?: Buying an eSim (like Airalo) before you land is more convenient as you'll have data the second you step off the plane. However, physical SIMs at the airport are cheaper and offer more data for the price.
Can I top up my credit later?: Yes. If your data runs out, you can buy top-up vouchers at any 7-Eleven store across Thailand. Just give the clerk your phone number and the amount you want to add.