Generator fuel planner
Put a daily price on generator runtime.
Estimate fuel use from generator size and load, or enter your own fuel rate. Add daily runtime and local gasoline price to compare planning costs.
Start with your numbersExample, not live fuel data
About $5.25 per day
4,250 W · moderate load · 4 hours · $3.50 per gallon
The same fixed calculation powers the form below.Your inputs
Use the example or your own fuel rate.
Choose the source that fits your information, then enter daily runtime and local gasoline price.
The method
Know which fuel rate drives the answer.
The calculation stays simple so you can compare scenarios. Generator design and operating conditions still matter.
Read the calculation method and sources
- 01
Choose the fuel-rate source
Use the size and load estimate, or enter your own US gallons-per-hour rate from your manual or records for a similar load.
- 02
Enter the active inputs
For the curve, use rated running watts and a broad load level. For your own rate, enter US gallons per hour greater than zero.
- 03
Add runtime and gasoline price
Enter daily generator runtime and replace the example gasoline price with your local gasoline price.
- 04
Read the planning estimate
Review estimated gallons per hour and cost per day, week, and 30 days.
What the estimate means. The size and load mode uses one fixed planning curve across generator sizes and three broad load choices. It is not a lookup for a specific make or model. The own-rate mode uses the number you enter without applying that curve. Cost equals gallons per hour multiplied by daily runtime and price per US gallon. Weekly and 30-day totals assume the same daily use. Actual fuel use changes with generator design, fuel, maintenance, altitude, temperature, and loads that cycle on and off.
Manufacturer context. Honda lists the EU2200i with a 0.95 gallon tank, 8.1 hours at one-quarter load, and 3.2 hours at rated load. Cummins lists the gasoline Onan QG 4000 at 0.5 gallons per hour at half load. These examples show model variation. They do not directly create the curve used here.
Honda EU2200i official specifications, accessed August 23, 2026. Cummins Onan QG 4000 official specification, January 2025, accessed August 23, 2026.
Choosing solar equipment for these loads? Use the Solar Sizing Planner to estimate array and battery capacity from your appliance use, location, and planning months. Keep that capacity estimate separate from this calculator's fuel-cost estimate.
Plan, then forecast
Compare generator cost here. Plan solar days in SunPlanner.
This calculator helps compare fuel-cost scenarios. SunPlanner estimates solar production for the array and location you enter.