Running a natural gas generator costs $0.50–$3.50 per hour depending on the generator size and load, making it the cheapest fuel option for standby power. A typical 20kW home standby generator at 50% load costs roughly $1.50–$2.00 per hour to run on natural gas in 2026, or about $36–$48 per day.
Natural gas generators have a massive cost advantage over gasoline and propane because the fuel itself is cheap ($1.00–$1.60 per therm nationally) and the supply is continuous — you never need to refuel, schedule deliveries, or worry about running dry during a multi-day outage.
Natural Gas Prices in 2026
Natural gas prices in the U.S. vary significantly by region. The national average residential rate in early 2026 is approximately $1.20 per therm (100,000 BTU).
Unit Conversions: 1 therm = 100,000 BTU = approximately 1 CCF (100 cubic feet) of natural gas. 1 MCF (1,000 cubic feet) = 10 therms. Your gas bill may use therms, CCF, or MCF — check which unit your utility uses before calculating costs.
Natural Gas Consumption by Generator Size
Generator manufacturers publish fuel consumption rates in cubic feet per hour (CFH) at various load levels. Here is what the most popular home standby generators actually consume.
To convert CFH to cost: divide CFH by 100 to get CCF per hour, then multiply by your price per CCF (roughly the same as price per therm).
Example: A 20kW generator at 50% load uses 200 CFH. That is 2.0 CCF per hour. At $1.20 per CCF, your cost is $2.40 per hour.
Hourly Running Costs by Generator Size
Here is the cost breakdown you came for — exact hourly costs at 2026 natural gas prices.
Most homes during a power outage run at 40–60% of generator capacity on average, even with load management cycling appliances. Use the 50% load column for the most realistic cost estimate.
Daily and Weekly Running Costs
For extended outages, here is what you can expect to pay per day and per week.
Real-World Example — Northeast Winter Storm: A homeowner in Connecticut with a 22kW Generac runs their generator for 4 days during an ice storm. At 50% average load and a local gas rate of $1.50/therm: 225 CFH × 96 hours = 21,600 CF = 216 therms. Cost: 216 × $1.50 = $324 for 4 days of whole-home power. The same outage on a gasoline portable would cost $500–$700.
Real-World Example — Texas Summer Heat: A homeowner in Houston with a 20kW standby runs their AC-heavy load for 3 days during a grid stress event. At 65% average load and a Texas gas rate of $0.90/therm: 240 CFH × 72 hours = 17,280 CF = 172.8 therms. Cost: 172.8 × $0.90 = $155.52 for 3 days. That works out to $2.16/hour or about $51.84/day.
Real-World Example — Weekly Exercise/Testing Cost: A 20kW standby generator runs its automatic weekly exercise cycle for 30 minutes at approximately 50% load. Consumption: 200 CFH × 0.5 hours = 100 CF = 1.0 therm. At $1.20/therm, each weekly test costs $1.20. Annual testing cost: roughly $62.40 — far cheaper than propane or gasoline testing.
Natural Gas vs. Other Fuels: Annual Cost Comparison
Over the course of a year with typical outage events and weekly testing, the cost differences between fuel types become substantial.
Over 10 years, a natural gas generator saves approximately $4,600–$5,400 in fuel costs compared to propane or gasoline. That savings alone can cover a significant portion of the generator installation cost.
How Natural Gas Supply Works During Outages
A common concern is whether natural gas remains available when the power goes out. The answer is almost always yes.
Natural gas distribution systems use pressure in the pipeline to push gas to your home. This pressure is maintained by compressor stations that have their own backup power. Gas distribution lines are buried underground, protecting them from wind, ice, and falling trees — the main causes of electric outages.
There are rare exceptions. Direct damage to a gas main from earthquakes, flooding, or construction accidents can interrupt supply. Some utilities may also shut off gas as a safety precaution during major natural disasters.
In over 95% of power outage scenarios, your natural gas supply will continue without interruption.
While natural gas supply is highly reliable during outages, it is not 100% guaranteed. If you live in an earthquake-prone area or a flood zone, consider having a backup propane tank as a secondary fuel source. Some generators offer dual-fuel (NG/LP) capability.
Gas Line Sizing for Generators
Your existing natural gas line may not have enough capacity to supply a large generator on top of your furnace, water heater, stove, and dryer. Generators require significant gas flow.
If your gas meter is far from the generator pad, or if you have many gas appliances already on the line, you may need a gas line upgrade. This typically costs $500–$2,000 and includes a new dedicated line from the meter to the generator.
Your installer should perform a gas line sizing calculation (per NFPA 54 / International Fuel Gas Code) before installation to ensure adequate supply.
Natural Gas Generator Cost Calculator
Tips for Reducing Natural Gas Generator Costs
Even though natural gas is already the cheapest fuel, you can reduce costs further.
Use load management. Smart load-shedding modules cycle high-draw appliances so your generator runs at a consistent 50–70% load instead of spiking to 100%. This improves fuel efficiency and reduces hourly costs.
Set realistic thermostat targets. During an outage, set heat to 66°F and AC to 78°F. Each degree adjustment saves roughly 3% in fuel consumption for the HVAC load.
Turn off non-essential circuits. Pool pumps, hot tubs, EV chargers, and electric dryers are luxuries during an outage. Turning them off can reduce your load by 30–50%.
Negotiate your gas rate. If you have a choice of natural gas suppliers (available in deregulated states like Texas, Ohio, and Pennsylvania), shop for a lower per-therm rate. Even $0.10/therm savings translates to meaningful cost reductions during extended outages.
Key Takeaways:
- A 20kW natural gas generator costs $2.40/hour at 50% load ($1.20/therm).
- Daily cost for a 20kW unit at 50% load: approximately $57.60.
- Natural gas is 50–70% cheaper than gasoline and 40–60% cheaper than propane per kWh.
- Over 10 years, natural gas saves $4,600–$5,400 in fuel vs. propane or gasoline.
- Natural gas supply stays on during 95%+ of power outages.
- Check your gas line capacity before installing — larger generators need bigger pipes.
- Weekly exercise testing costs only $1–$2 per week on natural gas.
Frequently Asked Questions
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