Can I upgrade my 30-day visa exempt entry to a 90-day tourist visa in Thailand?

and just so you're clear, you DIDN'T enter on a 30 day visa :O There is no such thing ;) You entered on a 30 day visa exempt entry (meaning you showed up without having bought a visa from a thai consulate before you came here and were stamped in for free for 30 days with NO visa) :P

You can as people said get a 30 day extension for 1900baht at your immigration office AND there's no need to wait for this current stamp to run out because they ADD the 30 days to your current expiration date.

IF you want to get a REAL tourist visa you need to go to a thai consulate in another country and BUY one. That would get you stamped in for 60 days when you enter thailand and you could extend it for 30 more days at the immigration office for 1900baht

The closest thai consulate to you is the one In Vientiane Lao (it requires an online booking to make an appointment to apply for a tourist visa).

Good Luck

Yes you can apply for a 30 day Extension of Stay at your local Immigration Office.

You can only extend things by another 30 days. You don’t have any visa, you have a visa exempt stamp.