Home Postcode finder VIC St Helens Plains St Helens Plains postcode VIC St Helens Plains is a locality in Victoria covered by postcode 3401. Postcode 3401 State or territory Victoria (VIC) Region Vic Far Country Add a free St Helens Plains business listing Be the first listing in St Helens Plains Common questionsWhat is the postcode for St Helens Plains?St Helens Plains, VIC has the postcode 3401.What state is St Helens Plains in?St Helens Plains is in Victoria (VIC).Does postcode 3401 cover more than one suburb?Yes. Postcode 3401 covers 33 localities, so the postcode alone does not identify St Helens Plains. Browse other postcodes in Victoria, or widen the search to every Australian postcode.