What a natural-gas standby generator costs to run

Updated July 23, 2026 · Reviewed against the current BackupAtlas dataset

The math, step by step

Manufacturers publish a generator's natural-gas consumption in cubic feet per hour (ft³/h) at a stated load — almost always half load, which is a reasonable stand-in for typical outage operation (a furnace, refrigerator, some lighting and electronics). Converting that to a dollar figure takes two steps:

1. Cubic feet to therms: natural gas carries roughly 1,030 BTU per cubic foot, and a therm is defined as 100,000 BTU, so 1 therm ≈ 97 ft³. A generator burning X ft³/h for 24 hours uses (X × 24) ÷ 97 therms per day.
2. Therms to dollars: multiply by the local price per therm. This page uses the EIA's national average residential rate, $1.45/therm — your utility bill will show your actual rate, which can vary from well under $1 to well over $2 per therm depending on region and season.

Cost per day of continuous operation, by model

Every home standby generator in the database with a published natural-gas half-load consumption figure, at $1.45/therm:

Table regenerates from the current dataset. See any model's own page for its full specifications and source link.

Weekly exercise cycles

Standby generators run a brief self-test on a schedule — commonly factory-set to somewhere in the 5–20 minute range and adjustable in the controller — to keep the engine lubricated and confirm it will start when needed. At a typical mid-size unit's half-load consumption, a 12-minute weekly test burns a small fraction of a day's worth of gas: roughly one-fiftieth of the 24-hour figures above, or well under a dollar a week for most models at national average rates. The exact self-test duration and frequency are configurable per installation — check the generator's controller settings or ask the installing electrician, since this page's dataset does not carry a per-model exercise-cycle spec.

Assumptions (the honest part)

• Half load, not full load. Manufacturers publish consumption at a stated load point — usually half load — because full-load fuel consumption is higher and lighter loads are lower, but not linearly: a generator idling well under half load can still burn a disproportionate share of its half-load rate due to engine overhead. Treat these figures as a planning estimate for typical outage use, not a guarantee for your specific load profile.
• National average pricing. $1.45/therm is a U.S. average; substitute your utility's actual rate — the fuel cost tool lets you enter your own price and hours per day for any generator class.
• Fuel cost only. This is gas consumption, not total cost of ownership — it excludes maintenance, oil changes, the ATS, and the installation itself.
• Meter and line capacity are a separate question. Running a generator on natural gas doesn't cost anything extra to "activate" the gas line, but the meter and line size must be confirmed by a gas utility or plumber to handle the generator on top of a furnace and water heater running at the same time — see the portable vs standby guide for the installation picture.

For a quick estimate on a different generator class or fuel — gasoline, propane, or natural gas — use the generator fuel cost comparison tool, which applies the same published-consumption method across every class in the database.

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