Propane Gas Consumption Chart. Calculating propane gas consumption is based on the burner size. For example, if a burner uses 22,875 BTU per hour, it will last 4 hours on a gallon of propane, which contains 91,502 BTU. You simply divide the energy content of the propane by the burner consumption: 91,502 ÷ 22,875 = 4.