You can enter an amount and built-in Cost of Living Calculator will determine how much more (or less) you need to maintain same standard of living in another city. It takes into consideration current prices in your current city and the city you are considering to move to. If you enter how much you need for living in current city, you'll get approximate info how much you will need in another city. This tools works with net earnings so don't forget to subtract an income tax.
This tool allows comparison for more than 300 cities worldwide. It shows recent gathered prices at this website. Prices include housing, utilities, transportation, restaurants, etc.