This varies from month to month, but at the time of writing of this FAQs section, the average gallon of natural gas in the U.S. is priced at $2.19, whereas propane goes for about $2.67. As stated above, propane is more expensive, but it also produces more than 230% more heat than natural gas for the same amount of gallons. In fact, the price per propane gallon would have to reach +$5 to argue that natural gas is preferable considering costs alone.