Type your answer here... there are around 91,600 BTUs in agallon of propane. The standard BBQ sized bottle of propanecontains 11 pounds of propane. Propane weighs about 4.2 pounds pergallon, so that 11 pounds of propane is about 2.5 gallons in itsliquid state. That means there is 91,600 BTUs/Gal times 2.5 gallonsso a BBQ sized tank of propane contains about 2.3 million BTUs. Ifyour BBQ has a 50,000 BTU burner, on high heat, it will last a bitover 4 and half hours of run time.