Each propane tank has a gauge that shows how much fuel is currently in the tank. When we fill a propane tank, we only fill it to 80% capacity to allow for the natural expansion that can happen in warm weather. Please keep in mind that weather conditions and your lifestyle can impact the amount of propane you use. If you have company over the winter and the weather is extremely cold, we recommend you take a look at your gauge and contact us when it gets close to 30%.