Cost of living in Kazan' (Russia) is 21% more expensive than in Łódź (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 286 prices entered by 30 different people.
For example, you would need at least 8,362 zł (руб 149,172) in Kazan' to maintain the same standard of living that you can have with 6,900 zł in Łódź.