Cost of living in Santiago de Compostela (Spain) is 18% cheaper than in Andorra la Vella (Andorra)
This comparison is lacking data. It provides a decent comparison, but it is not yet reliable. It is based on 316 prices entered by 29 different people.
For example, to keep the same standard of living that would require €2,900 in Andorra la Vella you would need to make just about €2,390 in Santiago de Compostela.