For a 28,000-watt Generac running on propane, the factory fuel chart shows 3.97 gallons per hour at full load.
Since propane tanks are only filled to 80%, usable capacity is:
• 250-gal tank ≈ 200 gal → ~50 hours
• 500-gal tank ≈ 400 gal → ~100 hours
• 1,000-gal tank ≈ 800 gal → ~200 hours
Generac requires fuel systems to be sized for 100% load, so a 500-gallon tank is the practical minimum, and 1,000 gallons is strongly recommended for extended outages and cold-weather reliability.





