Cost of living in Aveiro (Portugal) is 20% more expensive than in Gdańsk (Poland)
This comparison has some inconsistent or sparse data. It already provides a reliable comparison but it is not bullet-proof. It is based on 361 prices entered by 50 different people.
For example, you would need at least 14,418 zł (€3,356) in Aveiro to maintain the same standard of living that you can have with 12,000 zł in Gdańsk.