Cost of living in Kaunas (Lithuania) is 26% cheaper than in Zaragoza (Spain)
This comparison is lacking data. It provides a decent comparison, but it is not yet reliable. It is based on 257 prices entered by 39 different people.
For example, to keep the same standard of living that would require €2,900 in Zaragoza you would need to make just about €2,153 in Kaunas.