Cost of living in Sydney (Australia) is 47% more expensive than in Zaragoza (Spain)
This comparison has some inconsistent or sparse data. It already provides a reliable comparison but it is not bullet-proof. It is based on 4,978 prices entered by 904 different people.
For example, you would need at least €3,964 (AU$6,315) in Sydney to maintain the same standard of living that you can have with €2,700 in Zaragoza.