Cost of living in Opole (Poland) is 51% cheaper than in Amsterdam (Netherlands)
This comparison is lacking data. It provides a decent comparison, but it is not yet reliable. It is based on 1,265 prices entered by 324 different people.
For example, to keep the same standard of living that would require €5,700 in Amsterdam you would need to make just about €2,818 (11,749 zł) in Opole.