For most U.S. homes, natural gas costs less to use than liquid propane (LP), but a utility connection can make switching expensive. LP typically costs $2.50-$4.00 per gallon, while natural gas commonly costs $1.20-$2.50 per therm on a delivered-bill basis; location, usage, equipment efficiency, and connection work determine the actual comparison.
| Item | Low | Average | High | Notes |
|---|---|---|---|---|
| LP fuel | $2.50/gal | $3.25/gal | $4.00/gal | Residential delivered propane; price varies by region and delivery size |
| Natural gas | $1.20/therm | $1.80/therm | $2.50/therm | Illustrative all-in residential bill rate |
| LP heating, 100,000 BTU input | $2.73 | $3.55 | $4.37 | About 1.09 gallons per 100,000 BTU |
| Natural gas heating, 100,000 BTU input | $1.20 | $1.80 | $2.50 | One therm contains 100,000 BTU |
| Fuel-system conversion | $1,000 | $3,500 | $10,000+ | Appliance changes, piping, tank work, or gas-main extension can raise total |
Assumptions: broad U.S. residential ranges, standard fuel heating values, and no unusually long utility-main extension.
What LP and Natural Gas Cost for Typical Home Use
LP is usually the more expensive fuel per unit of heat. One gallon contains about 91,500 BTU, so a $3.25-per-gallon delivery price equals roughly $3.55 per 100,000 BTU before appliance efficiency. A natural gas therm contains 100,000 BTU, making an all-in rate of $1.80 per therm less costly for the same input heat.
With a 95% efficient furnace, the illustrative average fuel-only cost is about $3.74 per 100,000 BTU of useful heat for LP and $1.89 for natural gas. Actual household bills also include fixed monthly charges, taxes, delivery fees, and equipment electricity. At typical delivered rates, natural gas can provide the same useful heat for about half the fuel cost.
These figures are not fixed national rates. Propane prices depend on delivery timing, supplier, tank ownership, and gallons ordered; natural gas rates depend on the local utility tariff, usage tier, and monthly charges. A low gas rate may look less favorable for a small user paying a substantial customer charge.
How Fuel, Labor, and Connections Shape the Quote
A fuel comparison is different from a fuel-switching estimate. A household already connected to natural gas can compare operating bills directly; a home without a gas main must account for the cost of access, service piping, appliance changes, and potentially a new LP tank if it stays with propane.
| Quote component | LP option | Natural gas option | What changes the price |
|---|---|---|---|
| Fuel supply | $2.50-$4.00/gal | $1.20-$2.50/therm | Local rates, season, contract, and usage |
| Appliance conversion or replacement | $150-$600 per convertible appliance | $200-$800 per appliance connection | Parts, burner setup, venting, and manufacturer approval |
| Interior gas piping | $500-$2,000 | $500-$2,500 | Run length, pipe size, access, and number of fixtures |
| Tank and related work | $0-$2,500 | $0-$1,500 | Existing tank, rental terms, removal, or new regulator |
| Utility service extension | Not applicable | $0-$10,000+ | Distance to main, utility contribution, street work, and permits |
| Labor and inspection | $300-$1,500 | $400-$2,000 | Local rates, job complexity, and code requirements |
Ranges are illustrative U.S. project estimates; a utility may cover some service-line work, while a remote extension can exceed $10,000.
Conversion kits are not available or appropriate for every appliance. A furnace or range designed for one fuel may need replacement rather than a simple adjustment, and venting or combustion testing may be required. Request separate line items for appliance work, piping, utility charges, permits, and tank handling.
Which BTU Rates and Appliance Efficiencies Change the Result
The most important operating-cost inputs are delivered fuel price and equipment efficiency. Compare the actual billed natural gas rate, not just a commodity headline price, with the propane price per gallon on a recent delivery invoice. Include fixed charges separately, especially if gas service would be used only for a fireplace or occasional cooking.
Efficiency changes the amount of fuel needed to deliver a given amount of heat. At 80% efficiency, a system requires 125,000 BTU of fuel input to provide 100,000 BTU of useful heat; at 95%, it requires about 105,300 BTU. The efficiency difference can narrow the fuel-price gap, though it does not typically erase a large per-BTU rate difference.
Capacity and pipe distance affect installation rather than the basic fuel comparison. A 60,000-BTU appliance has different gas-flow requirements than a 150,000-BTU furnace, and a long run or multiple appliances may require larger piping. For propane, a tank regulator and line must support the combined appliance load, particularly during cold weather when heating demand rises.
Compare cost per useful BTU, not gallons against therms or appliance nameplates alone. A practical calculation is fuel price divided by the heat available per unit, then adjusted for the appliance’s rated efficiency. For a detailed quote, use actual annual consumption and equipment efficiency rather than assuming every home uses the same amount.
Does a Gas Main Extension Pay Back Against an LP Tank?
Where a natural gas main is already at the property, a standard service hookup may cost little or several thousand dollars depending on utility policy and site work. If the main is across a road or far from the house, the extension can dominate the project budget. Ask the utility whether it offers a construction allowance, free connection, or contribution based on expected annual usage.
Compare the upfront cost with expected annual savings. For example, if the gas conversion costs $5,000 and lowers fuel spending by $800 per year, simple payback is about 6.3 years. That estimate excludes financing, maintenance differences, fixed monthly gas charges, and future price changes. If annual savings are only $300, the same project takes about 16.7 years to recover its initial cost.
Natural gas may be especially attractive for a home with substantial year-round consumption, such as space heating plus water heating and cooking. A low-use property may not recover a costly extension, even when gas is cheaper per BTU. Use annual bills and a written utility estimate to calculate payback before authorizing trenching or appliance replacement.
Why Propane and Utility Rates Differ by Region
Propane is delivered by truck and stored at the property, so rural distance, seasonal demand, supplier competition, and delivery quantity affect its price. A household with a larger tank and room to schedule a summer fill may receive a different rate than a small customer needing an urgent winter delivery. Leased tanks can also limit the choice of supplier.
Natural gas is commonly less expensive in areas with established pipeline networks, but not every community has service. Utility rates vary with local infrastructure, regulation, distribution charges, and climate. Cold-weather states may have higher winter bills because of greater consumption even when the per-therm rate is not unusually high.
As a rough budgeting adjustment, rural LP buyers may see delivered prices 10%-30% above a competitive suburban market, while urban gas service can be 10%-25% higher or lower than another utility territory. These are planning comparisons, not guaranteed regional premiums; local quotes can vary more than broad regional averages. Use the same month and comparable usage period when checking supplier prices.
What Removal, Permits, and Appliance Changes Add
A switch from LP to natural gas can require a licensed contractor to change appliance orifices, adjust regulators, verify combustion, and label equipment. Depending on the appliance, conversion labor and approved parts commonly run $150-$600 each; replacing a furnace or water heater instead can add several thousand dollars. Manufacturer instructions and local code determine whether a conversion is permitted.
Tank removal or abandonment may cost $200-$1,000 for an accessible aboveground tank, with underground tank work often costing $1,000-$3,000 or more if excavation or environmental checks are needed. A rented tank may need to be returned to the supplier, and unused propane may be subject to a refund or handling policy. Confirm ownership and terms before arranging removal.
Permits and inspections may add about $50-$500 for a straightforward residential gas alteration, though local fees and required upgrades differ. Older homes may need shutoff valves, bonding, venting updates, or additional piping. Ask whether the quote includes inspection, pressure testing, disposal, and restoration of disturbed walls or landscaping.
Three Home Scenarios Show the Price Difference
A 1,800-square-foot home with an existing LP furnace and no gas service might use 700 gallons annually for heat. At $3.25 per gallon, annual propane fuel is about $2,275 before delivery charges or appliance efficiency adjustments. A hypothetical gas rate of $1.80 per therm would cost about $1,530 for equivalent furnace input, producing roughly $745 in annual fuel savings.
A 2,400-square-foot home already connected to gas and using 1,000 therms yearly at $1.80 per therm would spend about $1,800 on fuel. Replacing an LP appliance with a natural-gas model in this case avoids a main extension, so the decision mainly depends on appliance price, installation, and whether the existing LP tank serves other equipment.
A rural 1,500-square-foot home using 500 gallons of LP annually at $3.75 per gallon spends about $1,875 on that fuel. If natural gas is not at the property and the utility estimates a $9,000 extension, even a $600 annual operating saving implies a 15-year simple payback. These examples exclude fixed charges and are comparisons, not predictions of an individual bill.
| Scenario | Fuel assumption | Estimated annual fuel | Added project cost |
|---|---|---|---|
| Existing LP heating | 700 gal × $3.25/gal | $2,275 | $0 if no work is needed |
| Equivalent gas heating | 850 therms × $1.80/therm | $1,530 | $1,000-$5,000 where service is nearby |
| Rural gas conversion | Comparable heat at lower unit rate | About $1,275 | $5,000-$10,000+ if a main extension is required |
Lower the Conversion Price Without Losing Necessary Safety
First, request a fuel-cost comparison using the last 12 months of propane deliveries and actual gas tariffs. Compare like-for-like heat output, include monthly gas customer charges, and test more than one propane delivery price. This prevents a large project from being justified using a temporary rate or an incomplete utility estimate.
Keep the scope limited to appliances that can be safely and legally converted. If an appliance is near the end of its service life, compare its replacement cost with the approved conversion kit and labor; converting an old unit may postpone, rather than avoid, a replacement expense. Avoid replacing equipment solely to change fuels unless the operating savings support the additional investment.
Ask the utility about service incentives and coordinate permitted work to reduce repeat visits. If several appliances need piping changes, completing the approved work together can avoid duplicate mobilization charges. Obtain at least two itemized contractor quotes and verify that both include the same pipe route, tank disposition, inspection, and restoration work.
Propane customers can also reduce operating expense without converting by comparing supplier offers, asking about fixed-price or pre-buy terms, and scheduling delivery before emergency conditions. Check tank ownership and minimum-fill requirements before switching vendors. The lowest practical total cost often comes from controlling project scope and comparing delivered rates, not simply choosing the fuel with the lower headline price.