Estimating Annual Generator Fuel Costs

What goes into the estimate

An annual fuel cost is not a single number on a generator listing. It is the result of 3 figures: how much fuel the engine burns in an hour at the load you plan to run, how many hours you run the generator in a year, and what you pay for a unit of that fuel.

The listing gives only part of that picture. The maker's page states the rated fuel use for the model, usually at a stated load. Run hours are your decision, not a listing promise. The price is set by your supplier, and it changes, so no listing carries it.

Start by reading the fuel type wording: gasoline, propane, natural gas, or a combination such as dual fuel or tri fuel. Each fuel is measured in a different unit, so the estimate for one fuel is not the estimate for another.

Reading fuel use on a listing

A generator listing may state fuel consumption in gallons per hour for gasoline, in pounds per hour for propane, or in cubic feet per hour for natural gas. The maker's page or the owner's manual states the figure for the model and usually notes the load at which it was measured.

Dual fuel and tri fuel listings name more than one fuel. The maker states a separate consumption figure for each fuel because each fuel carries a different amount of energy per unit of volume. The electrical output does not change, but the volume of fuel burned in an hour does.

For an installed unit, a standby listing may state natural gas consumption separately. This site has no measured figures of its own. Treat a stated run time or fuel use on a listing as the seller's statement, read the maker's page to confirm it, and compare listings on the figures both state.

Estimating your run hours

The hours you run in a year are your estimate. No listing or maker can tell you how many outages your area will have or how long they will last. That part of the estimate comes from your own plan, not from a product page.

Texas homes prepare before winter storm season and summer heat. The Texas Division of Emergency Management and Texas Ready pages describe general preparedness steps without giving outage figures. Read those pages, then set your own run schedule.

What you plug in changes the load, and a higher load burns more fuel in an hour. Matching a load to a generator is a question for the maker and a licensed electrician, not for a cost formula.

Keep the estimate a range, not a single number. Fuel use at your actual load, hours that vary with the season, and prices that move all widen the range. A range is a more honest plan than a precise figure.

• How many hours did you plan for a typical winter or summer event?
• Which appliances will you connect during those hours?
• What load does the maker state for the fuel use figure you are reading?

Fuel prices and suppliers

Gasoline is a fuel made from crude oil and other petroleum liquids, as the US Energy Information Administration explains. Propane is a hydrocarbon gas liquid that occurs as a gas at atmospheric pressure. Natural gas is a fossil fuel delivered by pipeline. The EIA pages linked below explain each fuel in plain terms.

Prices change by season, region, and supplier. The price you pay is set by the supplier you choose: a gas station for gasoline, a propane supplier for a tank, and the natural gas provider for piped service. None of those figures appear on a generator listing.

For a home on a propane tank, the estimate begins with the supplier's price per gallon of propane. For natural gas service, the rate applies to the gas itself. Ask the supplier for the current price and delivery terms, then add those to the fuel use figure from the maker.

Comparing fuel types on a listing means comparing the maker's stated consumption per fuel, not comparing prices the listing does not carry. The dual fuel guide compares models that accept more than one fuel.

Why this site gives no total

This site publishes buying guides, not measured data. It has no fuel consumption figures, no run time figures, no price records, and no appliance loads, so it cannot combine them into an annual cost estimate.

What the site can say: an annual fuel cost estimate is built from the maker's stated fuel use, your own run hours, and your supplier's price. Read fuel use on the maker's page, read the stated run time per tank on the listing if it is shown, and ask your supplier for the current price.

Compare generator listings on the details both state: fuel type, tank size, and run time at a stated load. After a season, revisit the estimate with the hours you actually ran and the prices you actually paid. That is the only way to build a number you can plan on.

What to pick for your situation

Questions

Can I compute fuel cost from the run time on a listing?

Only as a starting point. The run time on a listing is stated by the seller at a given load. Confirm the figure on the maker's page, then multiply by your planned hours and your supplier's price to build your own estimate.

Which fuel is cheapest for a generator?

The site gives no cost ranking. Fuel prices change by season, region, and supplier. Ask your supplier for the current price, then compare fuel types on the maker's stated consumption rather than on the listing alone.

Why do dual fuel listings show 2 consumption figures?

Each fuel carries a different amount of energy per unit of volume. The generator produces the same electrical output, but the volume of fuel burned in an hour differs between gasoline and propane. The maker states each figure.

Does this site state how much fuel a generator uses?

No. The site has no measured fuel figures. The maker's page or the owner's manual is the source for fuel use at a stated load.

What should I ask my fuel supplier before I buy?

Ask for the current price per unit of fuel, delivery terms if you use a tank, and whether the price changes by season. Add that price to the maker's stated consumption to build your estimate.