Cost of living in Poznan (Poland) is 8% 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 515 prices entered by 60 different people.
For example, you would need at least 7,467 zł in Poznan to maintain the same standard of living that you can have with 6,900 zł in Łódź.