How much propane do I have left

SOURCE: http://modernsurvivalblog.com/preps/how-to-tell-how-full-or-empty-your-propane-tank-really-is/#more-36698 Nearly everyone has the typical 20-pound (5-gallon) barbeque grill propane tank, and many preppers have stocked up with extra tanks for various reasons – but how do you accurately know how empty or full your tank really is? Here’s the best way to find out how much propane is left in your tank: