Some bank's ATMs allow up to 40,000 baht in a single withdrawal, not to be confused with a daily limit associated with a particular card/account.

Most ATMs have a physical limitation, i.e. the height of the dispensing slot, which results in a 20,000 or 25,000 baht limit.

Some say you can make an ATM card-based withdrawal inside a bigger bank branch at a full-service desk, in larger amounts and perhaps even without the 150 baht fee, YMMV.

I found this, on a brief search at thaivisa dot com:

scb, k bank, etc 20,000
bangkok bank 25,000
UOB 30,000
aeon 40,000


https://www.google.com/search?q=maxi...hrome&ie=UTF-8