Propane tanks come in many different shapes and sizes. They are listed in both pounds and gallons. The listed weight of a tank is the weight of the fuel in the tank and does not include the tank itself. The amount of time each tankful of propane lasts depends on how often you use them and how much fuel the appliance requires.
These are the small, portable canisters you can purchase at many types of stores, such as camping stores. These 1-lb. canisters are designed for use in small appliances such as portable camping stoves and lanterns. They don't contain their own valves and connect easily to their appliances, usually using a threaded fitting.
20 to 40 Pounds
Smaller tanks in the range of 20 to 40 lbs. are primarily designed for use on barbecue grills and other large, yet portable camping/cooking appliances. They can also hook up to RVs. Twenty-pound tanks hold around 4 gallons, 30-lb. tanks hold 7 gallons and 40-lb. tanks hold 10 gallons. These are the most common of the larger tanks and can last for eight to 40 hours, depending on the number of burners and BTU output of the grill.
60 to 100 Pounds
These size tanks are noticeably taller than the stocky-shaped 20- to 40-lb. tanks. The tank and gas combined can weigh up to 170 lbs. when filled. A 60-lb. tank of propane usually equals 15 gallons, and 100-lb. tanks hold 25 gallons. Their BTU output can be more than 2 million. Along with cooking and heating, these tanks can fuel tools such as acetylene torches.
Large Home & Commercial Tanks
The largest propane tanks are designed to provide full-time fuel for homes and other buildings. They contain from 250 to 3,000 gallons of propane for homes, and may be 30,000 gallons for commercial use. They can resemble oil and gas cars on freight trains, often need to be transported by a vehicle and should be installed by a professional. The amount of time the propane in these tanks last can vary depending on the building's size and insulation; the propane can last anywhere from a few weeks to several months.