You have a 6 gallon propane tank that can be filled to 80% capacity max. I just finishes a 30 day,3500 mile trip and used about 4 gallons. My fridge goes on electric when available and gas on the road. These units use very little propane. To be more efficient, as we use the freezer very little, I fill the extra space with the square orange juice containers to help keep it cold. I also really like my fridge monitor that I found on the Internet. It's an Acurite 00986 wireless digital freezer and refrigerator monitor. Lets me check the temps without opening the door and losing cold. It also warns me when I forget to turn it back on after parking on a very un-level rest area for lunch.