How the Generator Fuel Calculator works
Last data update: 2026-10-06.
Data
Seventeen gasoline models from three manufacturers — Honda, Generac and Champion — each read on 2026-10-06 from the manufacturer's own model page, owner's manual or specification table:
- Honda: EU2200i, EU3200i, EU7000iS, EB5000 and EB10000, from Honda Power Equipment's model pages. The live pages return "Access Denied" to automated requests, so the figures were read from the Internet Archive's captures of those exact Honda URLs, under the provenance rule in SPEC §12 decision 17; both URLs are recorded per row.
- Generac: GP2500i, GP3500iO, iQ3500, GP6500 / GP6500E and GP8000E, from the specification tables of their owner's manuals on generac.com, cited by part number, revision and page.
- Champion: seven gasoline-only models, from the Specs table of each product page on championpowerequipment.com.
Each row stores the manufacturer's inputs — tank capacity, published load point, published run time at that load, rated and maximum output — together with the tank, load and run time exactly as printed, the source URL, the document and page, and the date checked. No consumption rate is stored: rates are calculated from the stored inputs, so a hand-copied rate cannot drift from the figures it came from. No retailer listing, reseller specification sheet or third-party mirror was used.
A model is included only when its manufacturer publishes both the tank capacity and a run time at a named load. Generac manuals that publish a run time without naming the model they apply to were left out.
Formula
Both modes use one rate, derived from the stored tank capacity and the published run time at the chosen load; the mode decides whether that rate divides the fuel you have or multiplies the hours you need.
rate = tank capacity / published run time at the selected load
runtime hours = available fuel / rate
fuel needed = operating hours × rate
cost = fuel needed × price per matching unit
tankfuls = fuel / tank capacity
refuels = ceil(fuel / tank capacity) − 1
1 US gallon = 3.785411784 litres
Rounding happens only on display; the arithmetic runs at full precision. A rate must be greater than zero. Fuel, hours and price may be zero, and zero is answered with zero rather than an error or a division. Empty, negative, NaN, infinite and unsupported-unit inputs are rejected with a message rather than coerced to a number. In runtime mode with "One tankful" selected, fuel above the model's tank is refused with a message instead of being treated as one continuous run.
What is deliberately not computed
No interpolation or extrapolation between the published load points. No hidden safety multiplier. No confidence range. No time for refuelling, which no manufacturer here publishes as a number. No conversion of a wattage-sizing total into an average load. Propane and natural gas are not supported.
Change log
- 2026-10-06 — the runtime and fuel consumption calculators merged into this one calculator with two modes (SPEC §12 decision 37). Dataset extended from three Honda models to seventeen models from Honda, Generac and Champion; the three Honda rows re-checked. Tankful and refuel counts added.
- 2026-09-19 — first draft as two separate calculators; three Honda models.
Cite this page
GridComfort, "Generator Fuel Calculator," gridcomfort.com. Figures from Honda, Generac and Champion manufacturer publications, checked 2026-10-06.