The FireCan has a heat output of about 38,000 BTU/hr. on its high setting. In general, 1 gallon of propane can output about 91,500 BTU. Our 5 lb. Gas Growlers hold roughly 1.2 gallons of propane, so a full Gas Growler will run the FireCan on max setting for approximately 2.5 - 3 hours. High altitude and low temperatures can affect propane burn efficiency, so these numbers may vary depending on conditions.