Generator Fuel Consumption Calculator
Calculate total gallons required and runtime per full fuel tank across 25%, 50%, 75%, and 100% generator electrical loads.
Tank Sizing & Outage Duration
Load-Adjusted Fuel Consumption Equation
Adjusted Burn Rate (Gal/hr) = Base 50% Rate × [0.4 + (Load % ÷ 100) × 1.2] | Tank Runtime = Tank Gallons ÷ Burn Rate- Base 50% Burn Rate: Standard manufacturer specification (e.g. 0.60 gal/hr).
- Load Percentage: Electrical demand relative to generator maximum continuous capacity.
- Fuel Tank Capacity: Usable liquid storage volume in generator integrated tank.
Step-by-Step Worked Example
Calculation Steps:
How to Use This Calculator
Assumptions & Limitations
- Fuel consumption increases non-linearly as electrical motor loads approach 100% capacity.
- Assumes fresh fuel and clean carburetor air filter.
Frequently Asked Questions
How long will 5 gallons of gas last in a portable generator?
In a typical 4,000W to 5,500W generator running moderate household loads (50% capacity), 5 gallons will last approximately 7 to 9 hours. In a smaller 2,000W inverter generator, 5 gallons can last 18 to 24+ hours.
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