We have a 9500 that I've gotten 12hrs out of running the boiler, well pump, fridge, lights, etc with 6.6 gallon capacity. This is at night when the load is under 25% of max capacity. During the day I'll throw on a stove burner, dishwasher, washer (none at the same time) and I get about 10hrs. This past storm I went through 10 gallons a day. I keep 25gallons on hand.