Question 1

How much gas does a 5000 watt generator use per hour?

Accepted Answer

A 5,000-watt generator at 50% load (2,500W) consumes approximately 0.5–0.7 gallons of gasoline per hour. At 100% load (5,000W), consumption rises to 0.9–1.1 gallons per hour. Over 8 hours at 50% load, expect 4–6 gallons total — roughly $14–$21 at current prices.

Question 2

Is propane or gasoline cheaper to run a generator?

Accepted Answer

It depends on local prices and generator efficiency. Propane typically costs $2.50–$4.00 per gallon versus $3.00–$4.50 for gasoline, but propane has lower energy density — you burn more gallons to produce the same power. Overall, propane and gasoline are usually within 10–20% of each other in cost. The bigger advantage of propane is indefinite storage life and more reliable startup after long storage.

Question 3

How much does it cost to run a generator for 24 hours?

Accepted Answer

Running a 5,000-watt generator at 50% load for 24 hours on gasoline costs approximately $40–$65. For a 10,000-watt generator at 50% load, expect $75–$120 per day. Natural gas is typically the cheapest option for standby generators: a 14kW standby running 24 hours on natural gas might cost $20–$35 depending on your gas rates.

Question 4

How much propane does a 7500 watt generator use?

Accepted Answer

A 7,500-watt propane generator at 50% load uses approximately 1.0–1.4 gallons of propane per hour (propane has lower energy density than gasoline, so consumption is higher per hour). Over 8 hours at 50% load, expect 8–11 gallons. A standard 20-lb BBQ tank holds 4.7 gallons of propane — enough for roughly 3–5 hours at 50% load.

Question 5

How much natural gas does a standby generator use per hour?

Accepted Answer

Natural gas consumption is measured in cubic feet (cu ft) or therms (1 therm = 100 cu ft). A 14 kW standby generator uses approximately 200–250 cu ft of natural gas per hour at full load — about 2–2.5 therms. At typical rates of $1.00–$1.50 per therm, that's $2–$3.75 per hour to run a 14 kW generator at full load.

Question 6

What size generator is most fuel efficient?

Accepted Answer

Fuel efficiency isn't just about generator size — it's about the match between generator size and load. The most fuel-efficient setup is a generator running at 50–75% of its rated capacity. An inverter generator is inherently more fuel-efficient than a conventional generator because it throttles engine speed down at partial loads. For maximum efficiency: right-size your generator (not too big, not too small) and choose an inverter model if available.

Fuel Type	Per Hour	Per Day	Per Week	Per Month	Per Year
Gasoline 0.374 gallon/hr · $3.50/gallon	$1.310	$10.48	$31.44	$136.71	$1640
Propane 0.479 gallon/hr · $3.00/gallon	$1.437	$11.49	$34.48	$149.95	$1799
Diesel 0.331 gallon/hr · $4.00/gallon	$1.323	$10.58	$31.75	$138.05	$1657
Natural GasCHEAPEST 0.427 therm/hr · $1.20/therm	$0.512	$4.10	$12.29	$53.43	$641

Fuel	Energy per Unit	Typical Price	Energy per Dollar
Diesel	37,800 Wh/gallon	$3.50–$5.00/gal	~8,400 Wh/$
Gasoline	33,400 Wh/gallon	$3.00–$4.50/gal	~8,350 Wh/$
Natural Gas	29,300 Wh/therm	$0.80–$1.50/therm	~24,400 Wh/$
Propane	26,100 Wh/gallon	$2.50–$4.00/gal	~7,900 Wh/$

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