Home Postcode finder QLD Callandoon Callandoon postcode QLD Callandoon is a locality in Queensland covered by postcode 4390. Postcode 4390 State or territory Queensland (QLD) Region Toowoomba Region Add a free Callandoon business listing Be the first listing in Callandoon Common questionsWhat is the postcode for Callandoon?Callandoon, QLD has the postcode 4390.What state is Callandoon in?Callandoon is in Queensland (QLD).Does postcode 4390 cover more than one suburb?Yes. Postcode 4390 covers 10 localities, so the postcode alone does not identify Callandoon. Browse other postcodes in Queensland, or widen the search to every Australian postcode.