Cooking Gas BTU Converter

Understanding Propane vs Natural Gas for Cooking

Propane (LP gas) and natural gas are the two main fuel types used in gas cooking appliances. While they both produce heat through combustion, they have significantly different energy content per unit volume, different operating pressures, and require different sized orifices in the burner. Converting an appliance from one fuel type to the other requires changing the orifice jets and potentially adjusting the air shutter and regulator pressure.

Energy Content Comparison:

The Conversion Factor:

Propane packs about 2.44 times the energy of natural gas per cubic foot, so to reach the same BTU output you need only 41 percent of the volume. Put the other way round, propane burns about 59 percent less gas by volume for the same heat. (An older version of this page said “40 percent less”, which is the reciprocal read the wrong way and understates the difference badly.)

The orifice change is not simply that same 41 percent, because propane is also delivered at a higher pressure and is a heavier gas. Flow through a jet scales with the orifice area and with the square root of pressure divided by specific gravity, and propane wins on pressure (11 inches water column against 7) while losing on density (1.52 against 0.60). Netting those out, a propane orifice ends up around half to 60 percent of the natural gas orifice area, which is roughly 72 to 77 percent of its diameter. Going the other way, natural gas jets are about 165 to 195 percent of the propane area.

Do not drill jets to hit a number off a page. Orifices are sold pre-drilled to the appliance manufacturer’s chart, and the conversion kit for your specific model is the only correct source.

Typical Cooking Burner BTU Ratings:

Cost Comparison:

The cost per BTU varies by region and current market prices. In general, natural gas costs approximately 60 to 70 percent less than propane per BTU in areas where both are available. Natural gas is delivered through underground pipes with no storage tank needed. Propane requires a tank on your property and periodic refills, which adds delivery charges. However, propane is available in rural areas where natural gas pipelines do not reach.

Safety Differences:

Natural gas is lighter than air (specific gravity 0.60) and rises when leaked, making it easier to detect and ventilate. Propane is heavier than air (specific gravity 1.52) and sinks to the lowest point, which makes leaks more dangerous because propane can pool in basements, crawl spaces, and low-lying areas. Both gases are odorized with mercaptan (the distinctive rotten egg smell) to aid leak detection. Always have gas work performed by a licensed technician and ensure proper ventilation in any kitchen using gas appliances.

Altitude Adjustment:

At higher altitudes, gas appliances produce fewer BTU because the thinner air contains less oxygen for combustion. The rule in NFPA 54 is a 4 percent reduction for every 1,000 feet (305 meters) above 2,000 feet (610 meters). Note the threshold: the first 2,000 feet cost you nothing, and the derate is counted only on the elevation above that.

So a 15,000 BTU burner at 5,000 feet (1,524 meters) is 3,000 feet above the threshold, which is three steps of 4 percent, a 12 percent derate, and about 13,200 BTU. At 4,000 feet it would be 8 percent and 13,800 BTU. Getting the threshold wrong is an easy way to under-derate by a full step.