That's right, both the online calculator and the Post Office POS system seem to share the same data so anyone posting a heavy parcel semi-locally will be automatically overcharged.

This would apply in any area at or near the boundaries of two zones and in the worst case scenario could amount to an overcharge of nearly $20.

Any seller in an outlying area of a zone needs to be extremely careful in quoting freight as there is no way at present that AP outlets can get the calculation right.