Dual Fuel Generator Cost Calculator

Practical intro

Use this dual fuel generator cost calculator to compare gasoline and propane for a generator that can run on both. It helps estimate runtime, fuel cost, and practical tradeoffs when one fuel is cheaper, easier to store, easier to find, or better suited to the outage plan.

When to use this calculator

• Comparing gasoline and propane before buying fuel for a dual-fuel generator.
• Estimating which fuel should be used first during an outage.
• Planning backup fuel when gasoline availability may be uncertain.
• Understanding the cost tradeoff between stored propane cylinders and gasoline cans.

Input explanation

• Gasoline on hand is the gallons available for generator use.
• Gas burn rate should match the expected load in gallons per hour.
• Gas price is the actual cost per gallon.
• Propane on hand is entered in pounds when the calculator uses cylinder weight.
• Propane burn rate should match the generator manual or measured load in pounds per hour.
• Propane price should be entered per pound if the calculator uses pounds.

Formula or estimation method

Step-by-step worked example

With 10 gallons of gasoline at a 0.65 gal/hr burn rate, gas runtime is about 15.4 hours. At $3.75 per gallon, gas costs about $2.44 per hour. With 40 lb of propane at 2.1 lb/hr, propane runtime is about 19.0 hours. If propane costs $0.95 per pound, propane costs about $2.00 per hour.

Common mistakes

• Comparing gasoline gallons directly with propane pounds without using burn rates.
• Assuming propane and gasoline produce identical generator output.
• Ignoring cold-weather propane performance and cylinder vaporization limits.
• Forgetting fuel availability, storage safety, and rotation needs.
• Switching fuels without following the generator manual.

Planning notes and limitations

• Gasoline often provides strong output but needs rotation and careful storage.
• Propane stores cleanly in approved cylinders but may have lower output on some generators.
• A dual-fuel plan can preserve flexibility when stations are closed or propane exchange is easier to find.
• This calculator compares fuel runtime and cost only; it does not determine safe generator placement, transfer equipment, or electrical load size.

Backup power safety checklist

Before relying on the estimate, confirm the equipment manual, fuel or battery limits, ventilation needs, weather protection, cords, transfer method, and local requirements. Fuel-burning generators belong outdoors away from openings because carbon monoxide can be deadly. Electrical connections, transfer switches, high-current batteries, and permanent wiring should be handled under applicable code by qualified people.

Before you buy equipment

Use this result as a screening estimate, then compare it with rated running watts, surge watts, usable watt-hours, fuel availability, recharge time, maintenance, and installation requirements. A backup plan is safer when it starts with fewer essential loads and leaves reserve instead of assuming every rating can be used at the same time.