The other thing to check is what rate is baht converted to foreign currency. Does that bank ATM give the option for conversion by them or sending the charge in baht to be converted abroad? It is probably better, maybe much better, to have conversion done abroad. If the ATM does not offer the option of conversion here or there, where does the conversion happen, and at what rate? If you can't get an answer from the bank you prefer, try TMBThanachart (formerly Thai Military Bank) to see the rate you get on conversion abroad, then try an ATM (on same day if possible) at another bank where the conversion option is not presented when making an ATM withdrawal.