Generator Fuel Cost Calculator: Gas, Propane, Diesel per Hour

A generator burning 0.75 gal/h costs about $3.24 an hour on gasoline at $4.32/gal, $1.83 on propane and $4.71 on diesel at EIA’s current prices — enter your own consumption below.

$4.32/galGasoline (EIA weekly)

$2.44/galPropane (STEO winter)

$6.29/galDiesel (EIA weekly)

Updated September 2026 · Source: EIA Weekly Retail Gasoline and Diesel Prices (week of 2026-09-14); EIA STEO September 2026 residential propane forecast · next EIA update ~Oct 23

By SolarCostData Data Desk · Reviewed September 2026 · Corrections log

On this page: Calculator Table How we calculated Sources

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Fuel Fuel price ($ per gallon) — prefilled from EIA; use your pump or delivery price Fuel use at your load (gallons per hour) — from your generator's manual at the load you run; not measured here Hours run per day — 8 h Days Compare: grid electricity for the same load (¢/kWh, optional) — and the kW the generator is carrying Load carried (kW)

Fuel cost per hour: —

Per day: —

For the outage / trip: —

Gallons needed: —

Same kWh from the grid would cost: —

Cost = gallons per hour × price × hours × days. Gallons per hour comes from your manual at your load; the table below shows the arithmetic for common consumption rates. Estimate, not a quote.

## Fuel cost per hour and per day at EIA prices | Consumption at your load | Gasoline $4.319/gal — per hour / per 8-h day | Propane $2.44/gal — per hour / per 8-h day | Diesel $6.285/gal — per hour / per 8-h day | |---|---|---|---| | 0.25 gal/h | $1.08 / $8.64 | $0.61 / $4.88 | $1.57 / $12.57 | | 0.5 gal/h | $2.16 / $17.28 | $1.22 / $9.76 | $3.14 / $25.14 | | 0.75 gal/h | $3.24 / $25.91 | $1.83 / $14.64 | $4.71 / $37.71 | | 1 gal/h | $4.32 / $34.55 | $2.44 / $19.52 | $6.29 / $50.28 | | 1.5 gal/h | $6.48 / $51.83 | $3.66 / $29.28 | $9.43 / $75.42 | | 2 gal/h | $8.64 / $69.10 | $4.88 / $39.04 | $12.57 / $100.56 | {caption="Generator fuel cost per hour and per 8-hour day by consumption rate, at EIA national gasoline, propane and diesel prices"} Prices: gasoline and diesel are EIA's weekly US retail averages for the week of 2026-09-14; propane is EIA's STEO national residential forecast for the coming winter (delivered residential propane — a cylinder exchange is priced differently). The consumption column is a parameter, not a claim about any model: read yours off the manual's fuel-consumption line at the load you actually run, and remember that half load usually burns well under half the full-load figure.

Gasoline (EIA weekly): $4.32/gal
Propane (STEO winter): $2.44/gal
Diesel (EIA weekly): $6.29/gal
At 0.75 gal/h, gasoline: $3.24/hour
8-hour day, gasoline: $25.91
Consumption source: your manual, at your load

Why this number

A generator burning 0.75 gallons an hour costs about $3.24 an hour on regular gasoline at EIA’s current US average of $4.32/gal, $1.83 on residential propane at the $2.44 STEO winter forecast, and $4.71 on diesel at $6.29 — roughly $26, $15 and $38 for an 8-hour day. Fuel cost = gallons per hour × price × hours. The gallons-per-hour figure is the one number only your generator’s manual can give you at the load you run; the calculator takes it, the run-hours slider does the rest, and the grid line shows what the same kWh would have cost at your electricity rate.

Generator sizing pages tell you what it can run; this one tells you what running it costs. Three prices come from EIA and are refreshed automatically; the one number you supply is your generator’s fuel consumption at the load you actually carry.

Fuel cost per hour: —

Per day: —

For the outage / trip: —

Gallons needed: —

Same kWh from the grid would cost: —

Cost = gallons per hour × price × hours × days. Gallons per hour comes from your manual at your load; the table below shows the arithmetic for common consumption rates. Estimate, not a quote.

Frequently asked questions

How much gas does a generator use per hour?

It depends on the size and the load, which is why this page asks rather than assumes: the manual states fuel consumption at 25%, 50% and full load, and the real figure sits between them. Enter that number; the cost per hour is then just consumption × price, and the table shows the arithmetic for 0.25 to 2.0 gallons an hour.

Is propane or gasoline cheaper to run a generator?

Per gallon propane is cheaper ($2.44 against $4.32 at EIA’s current figures), but a gallon of propane holds about 91,500 Btu against roughly 114,000 for gasoline, so a dual-fuel unit burns more of it per hour for the same output. Compare on the manual’s consumption figures for each fuel, not on the pump price alone.

Is it cheaper than the grid?

No — a generator is backup, not a rate plan. At 0.75 gal/h and $4.32/gal carrying 4 kW, gasoline costs about $0.81 per kWh delivered, against a US average grid rate near 17–18¢. The grid line in the calculator makes that comparison for your own load.

How we calculated this

Fuel cost = gallons per hour (at your load) × price per gallon × hours per day × days. Gallons needed = gallons per hour × hours × days. The grid comparison is kW carried × hours × days × your ¢/kWh. Prices: EIA weekly US retail gasoline (regular, all formulations) and No. 2 diesel; propane is the EIA STEO national residential forecast for October–March, refreshed when EIA publishes.

Sources: U.S. Energy Information Administration (EIA) electricity rates · DSIRE incentive records · public IRS/OBBBA guidance. Figures are modeled estimates, not quotes or tax advice. See our methodology.

Where to go next

Winter heating cost hub — The same propane price on the heating side, converted to cost per MMBtu.
Home battery payback calculator — The battery alternative for outages — sized from the loads you tick.
Electricity cost calculator — What the loads you are backing up cost on the grid.
EV vs gas cost calculator — The same EIA gasoline price applied to driving.