On average, it costs $2.51 more to fill a conventional car with a gallon of gas than to charge an electric car to go the same distance, according to the Department of Energy’s new eGallon tool. It may be an even bigger difference in your area, which is why this tool lets you choose your state to see just how much you would save by going electric.

In North Dakota, for instance, the difference is almost $3. Other states like Iowa, Kansas, and Missouri aren’t far behind, and there are 16 states where charging your electric car costs less than a buck per gallon equivalent.

In fact, the only state where an electric vehicle doesn’t represent huge savings is Hawaii, where gas is $3.74 and electric is $3.69. But if you live in Hawaii, you don’t have a lot to complain about anyway.