Cost of Living Calculator
You can enter your salary and built-in Cost of Living Calculator will determine how much more (or less) you need to maintain your same standard of living.
It takes into consideration current prices at this website 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.
Then if you have a salary offer for another city, you can estimate how much you can save more (or less) by living in that other city.
This tool allows comparison for more than 300 cities worldwide. It shows gathered prices from the past 18 months at this website.
Prices include housing, utilities, transportation, restaurants, etc.