Cost of living in Stuttgart for a family

In addition to what others have answered here I would add that the housing market in German cities is very tight and especially challenging for arriving foreigners. One usually needs help finding a place from the employer or to have temporary accommodation until one finds a place. Almost no Germans will rent to someone from overseas before they arrive and can meet them. Also, houses are not just more expensive than apartments but much harder to find. In and around cities, the vast majority of accommodation is simply apartments rather than stand-alone houses. And when Beppi says private schools are expensive this means around 12000 Euros a year per child compared to free for the usually good public schools. But the subjects of accommodation and schools has been covered extensively on other threads on this site.