Fuel Consumption
0.19 gal/hr
Total
1.5 gal
Cost
$5.25
Per Hour
$0.66
Fuel Consumption Rate
0.19
gallons per hour
Total Fuel
1.5 gal
Total Cost
$5.25
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Inputs
Result
Base consumption = (5000/10000) × 0.75 = 0.375 gal/hr at full load. At 50% load: 0.375 × 0.50 = 0.1875, adjusted by gasoline BTU factor = 0.37 gal/hr. 8 hours × 0.37 = 3.0 gallons × $3.50 = $10.50.
Inputs
Result
Base = (7500/10000) × 0.75 = 0.5625 gal/hr at full load. Diesel efficiency factor = 120000/138000 = 0.87. At 75% load: 0.5625 × 0.75 / 0.87 = 0.37 gal/hr. Over 24 hours: 8.8 gal × $4.00 = $35.16.
Fuel consumption depends on generator size and load. A 5,000W gasoline generator at 50% load uses about 0.37 gallons per hour. At full load, that increases to about 0.75 gal/hr. Diesel generators are 15–20% more efficient, while propane uses about 15% more fuel by volume.
| Generator Size | 25% Load | 50% Load | 75% Load | Full Load |
|---|---|---|---|---|
| 3,000W | 0.11 gal/hr | 0.22 gal/hr | 0.34 gal/hr | 0.45 gal/hr |
| 5,000W | 0.19 gal/hr | 0.37 gal/hr | 0.56 gal/hr | 0.75 gal/hr |
| 7,500W | 0.28 gal/hr | 0.56 gal/hr | 0.84 gal/hr | 1.13 gal/hr |
| 10,000W | 0.37 gal/hr | 0.75 gal/hr | 1.13 gal/hr | 1.50 gal/hr |
Runtime depends on tank size, generator wattage, and load. A 5,000W generator with a 5-gallon tank at 50% load runs about 13.5 hours. At full load, the same setup lasts about 6.7 hours. Inverter generators are more efficient at partial loads.
Propane costs less per gallon ($2–3 vs $3–4 for gasoline) but has fewer BTUs per gallon. A propane generator uses about 15% more fuel by volume. At typical prices, propane costs about the same per hour as gasoline, but offers cleaner emissions and indefinite fuel storage life.
A typical home during an outage needs 5,000–7,500W for essentials (fridge, sump pump, lights, phone charging) or 10,000–20,000W for whole-house backup including HVAC. List your essential appliances and add their wattages, then add 25% safety margin.
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Last Updated: Mar 19, 2026
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