Is It Cheaper to Run a Generator on Gas or Natural Gas?

When people ask whether gas or natural gas is cheaper for a generator, they usually want to know what an outage will cost them per hour. That’s the comparison I’ll focus on here.

I also look beyond the fuel receipt. Power output, fuel availability, runtime, and the cost of getting natural gas to the generator can change which option makes sense.

Is Natural Gas Cheaper Than Gasoline for a Generator in 2026?

Yes, natural gas is generally cheaper than gasoline on an equal-energy basis. Current national pricing gives natural gas a meaningful cost advantage before generator-specific efficiency differences are considered.

As of August 31, 2026, the U.S. Energy Information Administration reported regular gasoline at about $4.071 per gallon. You can check the latest figures through the EIA gasoline price update.

The latest available national residential natural-gas figure was $24.09 per thousand cubic feet for June 2026. The EIA residential natural gas table shows how widely prices can vary by state.

Comparison	Gasoline	Natural Gas
2026 national price used	$4.071 per gallon	$24.09 per 1,000 ft³
Energy content	120,214 Btu per gallon	1,036 Btu per ft³
Approx. cost per 100,000 Btu	$3.39	$2.33
Approx. cost per million Btu	$33.86	$23.25
Refueling	Tank must be refilled	Continuous with utility supply
Typical generator output	Usually highest rating	Usually lower than gasoline rating

Generator fuel cost is the amount you spend to produce usable electricity from a specific fuel at a given load. Comparing only gallons against cubic feet doesn’t work because those units contain different amounts of energy.

The EIA’s Btu conversion data lists gasoline at 120,214 Btu per gallon and natural gas at about 1,036 Btu per cubic foot.

How Much Cheaper Is Natural Gas on an Equal-Energy Basis?

At the national prices above, natural gas is about 31% cheaper by fuel-energy cost. That doesn’t automatically mean every generator will cost exactly 31% less per operating hour.

One gallon of gasoline contains about the same raw energy as 116 cubic feet of natural gas. At the prices used here, that natural gas costs about $2.80 compared with $4.07 for the gasoline.

• Gasoline equivalent: 1 gallon = about 120,214 Btu.
• Natural-gas equivalent: About 116 ft³ supplies roughly the same fuel energy.
• Gasoline cost: About $4.07 for that energy.
• Natural-gas cost: About $2.80 for equivalent raw energy.
• Difference: Natural gas saves roughly $1.28 per gasoline-gallon-equivalent.

This calculation is useful for comparing fuel prices, not predicting an exact generator burn rate. Engines can have different efficiencies and fuel requirements when switching between gasoline and natural gas.

Your utility bill also deserves a closer look. Fixed monthly service charges shouldn’t necessarily be treated as an added generator expense if you already pay them for normal household gas service.

Why Does a Generator Make Less Power on Natural Gas?

A multi-fuel generator usually produces fewer rated watts on natural gas than on gasoline. That lower output is one of the biggest trade-offs behind the cheaper fuel.

For example, the Westinghouse WGen9500TF is rated for 9,500 running watts on gasoline but 7,500 on natural gas. The FIRMAN T07571 is rated for 7,500 running watts on gasoline and 5,500 on natural gas.

A larger DuroMax XP15000HXT narrows the gap somewhat. It lists 12,000 running watts on gasoline and 10,260 running watts on natural gas.

Generator	Gasoline Running Watts	Natural Gas Running Watts	NG Output Reduction
Westinghouse WGen9500TF	9,500 W	7,500 W	About 21%
FIRMAN T07571	7,500 W	5,500 W	About 27%
DuroMax XP15000HXT	12,000 W	10,260 W	About 15%

That’s why I never size a tri-fuel generator using only the largest number on the box. I use the rating for the fuel I expect to run most often.

If you’re still working out your household load, my generator power capacity guide explains running watts, starting watts, and sizing headroom.

When Can Gasoline Still Be the Better Choice?

Gasoline can still make more sense when maximum portable power matters more than the lowest fuel cost. It also wins when you don’t have natural-gas service at the property.

• Higher output: Many multi-fuel generators deliver their highest rated wattage on gasoline.
• Easy portability: A gasoline generator doesn’t need to remain beside a fixed utility connection.
• Simple setup: You don’t need to size a natural-gas line or add a dedicated quick-connect outlet.
• Remote use: Gasoline works at campsites, worksites, cabins, and properties without gas service.
• Short outages: The installation savings may matter more than fuel savings if generator use is rare.

Gasoline’s biggest weakness is storage and refueling. Keeping several approved fuel cans ready also takes planning and safe storage space.

If you want gasoline plus a long-storage backup fuel without adding natural gas, a dual-fuel portable generator can be the simpler middle ground.

How Do You Calculate Your Own Generator Fuel Cost?

The best calculation uses your local fuel price and your generator manufacturer’s consumption figure at the load you expect. National averages are helpful for comparison, but local numbers make the decision.

1. Find your gasoline price. Use the price you would realistically pay during an outage.
2. Find your natural-gas rate. Check the variable cost per therm, CCF, or thousand cubic feet on your utility bill.
3. Check fuel consumption. Look in the generator manual for gallons per hour, cubic feet per hour, or Btu per hour.
4. Match the load. Compare both fuels at the same electrical demand whenever the manufacturer provides that data.
5. Multiply usage by price. This gives your approximate fuel cost per hour.

For gasoline, the formula is simple: gallons per hour × price per gallon = operating cost per hour. A generator burning 0.8 gallon per hour with $4 gasoline costs $3.20 per hour for fuel.

For natural gas, multiply cubic feet per hour by your cost per cubic foot. If your bill uses therms, remember that one therm equals 100,000 Btu.

Don’t assume your gas line can feed any generator you buy. Pipe size, pressure, distance, other household appliances, and generator demand all affect whether the supply is adequate.

Which Fuel Is Better During a Long Power Outage?

Natural gas usually has the convenience advantage during a long outage when utility service remains available. You don’t have to stop the generator repeatedly to pour fuel into its tank.

That becomes important after storms when roads are blocked or nearby gas stations lose power. A natural-gas generator can continue operating as long as the gas utility keeps supplying the property.

• Natural gas: Best for long runtime and fewer refueling trips.
• Gasoline: Best for portability and maximum rated output on many models.
• Tri-fuel: Best when you want to switch fuels as availability changes.

There is one important limit: natural gas isn’t guaranteed during every emergency. Earthquakes, damaged utility infrastructure, shutoffs, or local service interruptions can affect supply.

That is why I like fuel flexibility for emergency equipment. My portable generator fuel system guide explains how gasoline, propane, and natural-gas setups differ mechanically.

Does Natural Gas Save Enough to Justify a Tri-Fuel Generator?

It can, especially if your home already has a suitable natural-gas connection. The economics become less attractive when you need expensive gas-line work just to use the third fuel.

Think about ownership cost, not only hourly fuel cost. The generator purchase price, plumbing work, permits, hoses, fittings, and electrical connection can exceed several years of fuel savings for a lightly used machine.

Natural gas becomes more compelling when you expect frequent or extended outages. Avoiding gasoline storage and repeated refueling also has value that doesn’t appear in a cost-per-Btu calculation.

Generator Safety Matters No Matter Which Fuel Is Cheaper

Gasoline and natural-gas generators both produce carbon monoxide. A cleaner or cheaper fuel does not make an engine-driven portable generator safe to operate indoors.

The U.S. Consumer Product Safety Commission says portable generators should run outdoors at least 20 feet from the home, with exhaust directed away from the building.

• Never run indoors: That includes garages, basements, sheds, and enclosed porches.
• Use CO alarms: Install working alarms on every home level and outside sleeping areas.
• Prevent backfeeding: Don’t improvise a connection through a household outlet.
• Use proper transfer equipment: Have panel-connected equipment installed correctly.
• Follow the manual: Fuel hoses, pressure, grounding, and clearances vary by generator.

The Electrical Safety Foundation International generator guidance also recommends a proper transfer switch when supplying a home’s electrical system.

For more fuel handling details, see my portable generator fuel safety guide.

Which Tri-Fuel Generators Are Worth Considering?

If natural gas looks like the cheaper option for your home, I’d focus on generators with clearly published output ratings for every fuel. These three cover different power needs.

Frequently Asked Questions

Is natural gas always cheaper than gasoline for a generator?

No. Natural gas is generally cheaper using current U.S. averages, but local fuel prices can reverse the result. You should compare your utility’s variable natural-gas rate with local gasoline prices and the consumption specifications for your exact generator.

How much natural gas does a generator use per hour?

Consumption depends heavily on generator size and electrical load. Manufacturer specifications may list natural-gas demand in cubic feet per hour or Btu per hour, so use the figure for your specific model instead of relying on a generic estimate.

Does a generator run longer on natural gas?

A natural-gas generator connected to a functioning utility supply can run without stopping for tank refills. The engine still needs scheduled oil checks, maintenance, and any runtime limits specified by the manufacturer.

Does natural gas reduce generator wattage?

Usually, yes. Many tri-fuel generators have a lower running-watt rating on natural gas than gasoline, sometimes by 15% to more than 25%, so always size your loads using the natural-gas rating if that’s your planned primary fuel.

Is converting a gasoline generator to natural gas worth it?

It can be worthwhile when the generator is compatible, your home already has adequate natural-gas capacity, and you expect long outages. A factory-built tri-fuel generator is often simpler because its fuel system and published wattage ratings are already designed for natural gas.

Final Takeaway: Gasoline vs Natural Gas Generator Cost

For most homes that already have natural-gas service, natural gas is the cheaper fuel to run. Using the latest national figures available in 2026, its raw energy cost is about 31% below gasoline.

Gasoline still offers higher output and better portability on many generators. If I were preparing for long home outages, I’d choose a properly sized tri-fuel model and keep gasoline available as a second option.

Before buying, compare the natural-gas wattage rating, local fuel prices, and the cost of a safe gas and electrical connection. That gives you a far more useful answer than comparing fuel prices alone.