Built-in Grill Natural Gas vs Propane | The Honest Fuel Choice

For a built-in grill connected to a home gas line, natural gas is the superior choice due to 3 to 6 times lower fuel costs and an uninterrupted supply, but propane is the only option for portability or when a gas line isn’t available.

Standing in front of a grill aisle deciding between two almost-identical built-in models, the only difference is the fuel hookup. One wants a natural gas line; the other runs on a propane tank. The gas you choose for a built-in grill is permanent—you won’t swap fuels without a conversion kit and a professional—so picking the right one on day one matters. Here is exactly how each fuel performs and which one your backyard actually needs.

The Practical Difference: Cost, Heat, and Where It Lives

Natural gas and propane are chemically different fuels that behave differently inside the same burner. Natural gas (mostly methane) delivers about 2.5 times less BTU per cubic foot than propane, but your grill compensates with larger orifice holes that let more gas flow. The peak flame temperature ends up nearly identical both fuels produce the same cooking heat on a properly configured grill. The real difference is in your wallet and your setup.

Natural gas costs roughly 1/3 to 1/6 the price of propane per unit of cooking energy. That savings adds up fast for a built-in grill you use weekly. The trade-off is permanence: once you pour a concrete island and plumb the gas line, that grill is anchored to that spot. Propane tanks are portable—you can wheel the grill to the driveway, pool deck, or porch—but you also have to refill them and watch for the tank running empty mid-burger.

Can You Convert a Propane Built-In Grill to Natural Gas?

Yes, but only with a manufacturer-approved conversion kit—never with a generic “universal” kit or by drilling out the orifices yourself. Natural gas runs at lower pressure than propane and needs larger orifice holes to pass the extra volume. A proper conversion involves three steps: swap the propane orifices for the natural gas set (the holes are visibly larger), replace the regulator with the lower-pressure natural gas version (some regulators let you flip a plunger to switch between LP and NG settings), and adjust the air shutters if your burners have them. The parts cost $50 to $150 for a legitimate kit.

A licensed professional should handle the gas-line connection anyway—running a natural gas line from the house requires permits and 2–4 hours of work—so have that same pro do the conversion. DIY conversions void most manufacturer warranties. If the idea of converting a propane built-in seems like a hassle, check our tested roundup of the best built-in propane grills for models designed for that fuel from the factory.

Safety Hazards Specific to Each Fuel

Both fuels produce carbon monoxide as a combustion byproduct—always grill outdoors. The difference is where a leak goes. Propane fumes are heavier than air and sink, so a leak near a low-lying enclosure or unvented island base can pool into a dangerous pocket. Natural gas fumes rise and disperse upward, which makes outdoor leaks less risky but still requires proper clearance from walls and overhead structures. After any conversion, always run a soap-and-water leak test on every new connection before lighting the grill.

Common Mistakes That Wreck a Built-In Setup

The most expensive error is buying a grill without confirming which fuel it uses. Reversing the hookup—running natural gas through propane orifices or propane through natural gas ones—causes poor flame, incomplete combustion, and a real safety hazard. Other frequent failures include assuming a universal conversion kit works on every brand (kits are model-specific), drilling out orifices yourself (irreversible and dangerous), and running a gas line without pulling the required local permits. A licensed installer fixes all of those in one visit.