How long will a 20 lb tank of propane run a generator?

A 20 lb propane tank holds roughly 4.7 gallons of propane and will run a generator for anywhere from 3 to 10 hours, depending on the generator's wattage output and how hard you're loading it.

The range is wide because load percentage drives everything. A DuroStar DS13000MX running at 25% load (about 2,625W) burns propane slowly — expect 8 to 10 hours from a standard 20 lb tank. Push that same generator to 50% load or higher and runtime drops closer to 4 to 5 hours. Smaller generators in the 4,000–5,000W class run more efficiently at lighter loads, which can stretch a 20 lb tank toward the higher end of that range. Also note that propane output on DuroStar dual-fuel models runs about 5% lower than gasoline output, so size your runtime expectations accordingly.

• A 20 lb propane tank contains approximately 4.7 gallons of usable propane fuel.
• DuroStar DS13000MX at 25% load (≈2,625W) on propane: estimated 8–10 hours per 20 lb tank.
• DuroStar DS13000MX at 50% load (≈5,250W) on propane: estimated 4–5 hours per 20 lb tank.
• Propane output on DuroStar dual-fuel models is approximately 5% lower than gasoline output at the same load.
• A 40 lb propane tank is DuroStar's recommended size for extended runtimes on MX-series generators.