Propane generators are a dependable option for backup power during outages. The answer depends on tank size, power output, and fuel consumption. For example, a 5,000-watt portable generator using a standard 20 lb tank can run for about 6 to 8 hours at half load.
This guide simplifies the factors that affect propane runtime, enabling you to prepare confidently, especially during natural disasters.
Grounded Electric, led by expert electrician Robert “Bobby” Mulholland and project manager Barret Abramow, installs propane generator systems across New Jersey.
Key Takeaways
- A generator’s runtime on propane depends on tank size, generator wattage, and power load; a 20 lb tank typically lasts 5–7 hours at moderate load.
- Larger propane tanks (250–1,000 gallons) can support standby generators for several days to over two weeks of continuous use.
- Runtime calculations utilize a simple formula: propane gallons divided by hourly consumption based on the generator’s load.
- Propane is cleaner and more stable than gasoline, but may cost more upfront; it’s preferred for long-term emergency use.
- Reducing electrical load, maintaining your generator, and using only essential circuits can significantly extend runtime.
How Long Does a Generator Run on Propane?
How long a generator will run on propane depends on your generator’s size and the amount of power you need. A 5,000-watt generator can run for 6 to 8 hours on a 20 lb propane tank.
Larger tanks and reduced loads can extend that time to several days. Planning your fuel storage and load usage helps improve reliability, especially for those relying on portable generators.
Estimate Runtime Based on Load and Tank Size
To estimate runtime, divide your tank’s capacity in gallons by the number of gallons of propane your generator consumes per hour.
For example, 4.6 gallons in a 20 lb tank ÷ 0.8 gallons/hour = around 5–6 hours. Higher loads reduce runtime. For a full breakdown of system sizing, load planning, and fuel needs, refer to our detailed generator guide.
Runtime Examples by Generator Wattage
Here are typical estimates with a 20 lb (4.6 gallon) tank:
- 2,000W: 8–10 hours at 50% load
- 5,000W: 6–7 hours at 50% load
- 7,500W: 4–5 hours at 50% load
- 10,000W: 3–4 hours at 50% load
Tank Sizes and Estimated Runtime
Larger propane tanks offer extended runtime:
- 100 lb tank: Up to 24 hours
- 250-gallon tank: 4–5 days
- 500-gallon tank: 7–10+ days
- 1,000-gallon tank: Up to 2 weeks
Are you unsure how long a propane tank lasts on a generator? Runtime varies by tank capacity, power output, and load. For example, a 100 lb tank may last longer in light use situations, but will burn faster during continuous high draw.
How Long Can a Propane Generator Run Continuously?
With proper maintenance and a reliable fuel supply, some generators can run for up to 200 hours. Generac-certified installations from Grounded Electric ensure safe, efficient, long-duration use with lower fuel consumption.
Knowing how long a propane tank lasts for portable generators is critical in planning for extended outages.
Propane vs Gasoline – Cost and Efficiency
Propane burns cleaner and stores more efficiently than gasoline. Gasoline costs less per hour, but propane is more stable and safer. If you’re weighing your options, this guide compares the pros and cons of a diesel generator vs a propane generator to help you decide which fuel type fits your needs best.
Runtime Formula Without a Calculator
Use this formula: propane gallons ÷ gallons/hour = estimated hours. A 24-gallon tank with a 1.2 GPH load = 20 hours. Always leave a buffer for surges.
500 Gallon Propane Tank Runtime for Generac
A 500-gallon tank can power a Generac generator for 7 to 10 days under average use. Grounded Electric’s certified systems match usage to tank capacity for best results.
Generator Run Time by Tank Type
Tank size matters. Portable tanks suit small jobs; fixed tanks support longer outages. Not sure where to start? Here’s how to choose a generator for your home.
Propane vs Gas Runtime
Gas offers more power per gallon, but propane provides cleaner emissions and better shelf life. For cold starts or long storage, propane is often preferred. Natural gas generators are another option for homes with utility gas connections.
LP Gas Runtime Basics
LP gas, also known as liquefied petroleum gas, is similar to propane. Runtime depends on load and tank size. Grounded Electric installs LP gas systems compliant with NJ codes.
Champion Generator Propane Runtime
A 3,800W Champion unit runs up to 10.5 hours on a 20 lb tank at 50% load. Larger tanks extend runtime.
Firman Generator Propane Runtime
The Firman 4550W model can run for 12 hours on a 20-pound tank. Performance depends on load and model.
Generator Runtime Calculation
Multiply tank gallons by runtime per gallon. For example, 23 gallons × 1 hour = 23 gallons per hour..
10,000W Generator on Propane
Consumes 1.5–2.0 gallons/hour. A 100 lb tank (23.6 gallons) offers 10–15 hours.
5,000W Generator on Propane
Uses 0.8 GPH. A 20-pound tank provides 5–6 hours of service; a 100-pound tank lasts 25–30 hours.
7,500W Generator on 20 lb Tank
Burns 1.2 GPH. Expect 3–4 hours on a 20 lb tank.
12,000W Generator on Propane
Uses 2.0–2.5 GPH. A 100 lb tank offers up to 10 hours. Larger tanks are better for long outages.
2,000W Generator on Propane
Highly efficient. Can last 10–12+ hours on a 20 lb tank.
Tips to Make Your Propane Last Longer
Shut off non-essentials, stagger usage, and keep filters clean. Maintain generators every 100 hours. To avoid risks, especially in enclosed spaces, learn more about carbon monoxide deaths from generators.
Propane generators are environmentally friendly and can provide cleaner energy than other fuel types.
Extend Runtime Habits
- Use only critical circuits
- Don’t run high-draw items together
- Clean filters and spark plugs
- Store propane in cool, ventilated areas
- Stay around 50–75% load
Propane Generator Runtime: How Long Your Tank Will Last
Propane runtime depends on tank size, generator wattage, and the load you place on the system. Small tanks power portable units for a few hours, while larger fixed tanks can keep a standby generator running for days. When you match your fuel supply to your power needs, you get steady, reliable performance in any outage.
Grounded Electric’s Generac-certified team can help you choose the right setup and ensure your system is ready for long, safe operation.
