The rule for a US licence
Thai law requires foreign drivers who are not ASEAN license holders to carry an IDP together with their home license. Police checkpoints are common, particularly around tourist areas, and the IDP is checked as a matter of course.
A digital or photographed IDP is not accepted anywhere in Thailand - the physical booklet must be carried.
You cannot obtain an IDP inside Thailand as a tourist. It must be issued in your home country before you travel.
This applies to motorcycles and scooters as well as cars, and your IDP must cover the vehicle class you are riding. Renting a scooter on a car-only permit leaves you uninsured.
Live in Thailand?
A licence issued in Thailand is what you drive on at home - an IDP translates a foreign licence, so it does not apply to you here. If your licence is from somewhere else, check that licence country: the rule depends on where the licence was issued, not only on where you are driving.
At the rental counter
Scooter rental shops often hand over keys without checking anything, which is not evidence the law does not apply. Riding uninsured after an accident is where this becomes expensive.
What the permit covers
An International Driving Permit is a translation of your licence into a standard multilingual booklet, issued under the 1949 and 1968 road traffic conventions. It is not a licence, and it is never valid on its own: you carry it with your own licence, and police expect to see both.
It is issued against the vehicle classes already on your home licence, and it never adds one. If your licence does not cover motorcycles, an IDP does not let you ride a scooter in Thailand; if it does not cover a heavier vehicle, the permit will not cover a camper or a minibus either. The permit restates what you already hold, in a form the local authorities can read.
Driving in more than one country?
Check every destination on your trip at once - Thailand is already filled in.
Check your tripOther destinations
Informational only, not legal advice. Requirements change and vary by length of stay, rental company, and vehicle class. Always confirm with the destination's embassy or your automobile association before you drive.