Propane Generator Fuel Calculator

A 20lb propane tank holds about 4.7 gallons of usable propane. Runtime depends on your generator size and load. For example, a 20kW generator at 50% load (1.9 gph) will run approximately 2.5 hours, while a smaller 7kW generator at 50% load (0.8 gph) can run about 6 hours. Use our calculator above for exact estimates based on your setup.

A typical home standby generator (20-24kW) uses 45-100 gallons of propane per 24 hours depending on load. At 50% load, expect around 45-55 gallons. At full load, consumption can reach 85-100 gallons. Smaller portable generators (7-10kW) use 18-48 gallons per day.

With a 250-gallon tank (200 usable gallons at 80% fill), a 22kW generator at 50% load (2.1 gph) would run approximately 95 hours or about 4 days. At full load, it would last about 51 hours or 2 days. Runtime increases significantly if you only run essential appliances.

Propane is often slightly more expensive per hour than gasoline, but propane has significant advantages: it stores indefinitely without degradation, burns cleaner (less maintenance), produces fewer emissions, and propane generators typically last longer. For emergency backup use, propane is generally the better choice despite slightly higher fuel costs.

Generac generators follow similar consumption rates to other brands. A Generac 22kW uses approximately 2.1 gph at half load and 3.9 gph at full load. A Generac 24kW uses about 2.3 gph at half load and 4.2 gph at full load. Always check your specific model's manual for exact specifications.

Key factors include: (1) Generator size (kW rating) - larger generators use more fuel; (2) Electrical load - running more appliances increases consumption; (3) Temperature - cold weather can increase usage by 10-15%; (4) Generator efficiency and age; (5) Altitude - higher elevations may affect performance. Operating at 50-75% load is most efficient.