Can my granddaughter extend her 30-day visa-free stay in Thailand?

When going to Thailand for 31 - 60 ( 90 )days, the 60 days touristvisa is the best option.

It is cheaper than visa excempt + 30 days extension.

No need of a onward ticket ( 90 days 1 onward ), if returnticket within 60 days.

It is easier to apply from the comfort of your home.

thaievisa.go.th

If visiting the nearest Thai Embassy website, you may find informations, that make it easier to apply online.

Not wasting holiday time to find, go to and waiting at a immigration office ( 90 you would need that ).

Then no need to leave Thailand in up to 90 days.

It completely depends on their passport country. Without that information it’s impossible to say what they could or couldn’t do.

Easiest way is to apply for 60 days tourist visa

If they have a passport from a country eligible for visa exempt, then they can receive a 30 day entry stamp and can apply one time for a 30 day extension.

But it's much simpler to apply for a tourist visa through the evisa system if they want to come for more than 30 days. Then they won't have to spend a day at the immigration office and the visa also costs less than the 1900 baht you pay for an extension.