Propane vs Natural Gas Grill: Cost Per Hour, Hookup and Conversion

Choose propane if

• No gas line runs to your patio, or the run would be long or cross a finished yard.
• You want to move the grill for the seasons, parties or a future house.
• You grill a few times a month, where the fuel savings are small.
• You rent and cannot add a gas outlet.

Choose natural gas if

• A gas stub or outlet already exists near the patio.
• You grill several times a week or run long indirect cooks.
• You never want to swap or haul a tank again.
• You are building an outdoor kitchen, where a hard-piped built-in like the Napoleon Built-In 500 Series 32 in. Grill Head (Natural Gas) makes sense.

Per unit of heat, usually yes. Propane holds 21,548 BTU per pound and about 4.24 pounds per gallon, so at $3.50 per gallon, 100,000 BTU of propane costs about $3.83. Natural gas is sold by the therm, which is 100,000 BTU, so at $1.50 per therm the same heat costs $1.50. A grill averaging 30,000 BTU per hour costs about $1.15 an hour on propane and about $0.45 on natural gas.

Now scale it to real use. 100 hours of grilling a year at that rate is about $115 in propane versus $45 in natural gas, a $70 difference. If you need a new gas line, compare your plumber's quote to that yearly savings: at light use, payback can take many years, while heavy users and outdoor kitchens recover it faster. Refill a tank rather than exchanging it when you can, because exchange tanks are commonly filled to about 15 lb instead of 20.

Only with the manufacturer's approved conversion kit for your exact model, installed as the instructions require, and many cart grills have no approved kit at all. Conversion is more than a new hose: natural gas needs larger burner orifices, a different regulator setup and sometimes different valves, because it is delivered at lower pressure and carries less energy per cubic foot. Never connect a propane grill to a natural gas line, or the reverse, without that kit; the result can be weak, unstable flames or dangerous oversized flames.

If a kit exists, it is sold by model number; search for natural gas conversion kits and match the part to your grill's manual before buying. If none exists, buy the grill in the fuel you have. Broil King, Weber and Napoleon all sell factory natural gas models, such as the Broil King Regal S 420 Pro Gas Grill (Natural Gas).

A typical hookup has a gas line run from the house supply to an exterior outlet with a shutoff valve, sized for the total BTU load and the length of the run, then a quick-disconnect hose to the grill. The line should be installed and pressure tested by a licensed plumber or gas fitter, and many jurisdictions require a permit and inspection. If the line runs underground, call 811 before anyone digs so buried utilities are marked. An undersized line is a common reason natural gas grills never get hot, especially if a patio heater or fire pit shares the same run.

A grill built for natural gas is designed to deliver its rated heat on natural gas, so a factory NG model should cook like its propane twin. Propane carries about two and a half times more energy per cubic foot, which is why its orifices are smaller, not why it cooks hotter. Where natural gas grills fall short, the cause is almost always the supply: a line too small for the load, a long run, low pressure or a kinked hose. If yours struggles to reach temperature, have a gas fitter check pressure at the grill before blaming the burners.