It is not only on International Sales, The AuPost Calculator can give misleading / Conflicting results, my latest conflict was over a postage Calculated online at $58.65 Entering the Dimensions Lx W x D Up to 22kg. When presented at Au Post Counter it was $99.65 to Post @ 21kg. Item including Post $150, less FVF $20.90 Less $99.65 Postage,  I didn't even cover Time to pack, Take to P/o & Upload the tracking info.