10/02/2026
That empty feeling in your tank this summer had nothing to do with how much you grilled.
A standard 20 pound cylinder is built to hold 20 pounds of propane, right around 4.7 gallons, yet the tanks waiting in those exchange cages outside the grocery store carry only 15 pounds. The steel never lost a single ounce. Back in 2008 the two biggest exchange companies cut the fill from 17 pounds to 15 and held the price steady, and by March 2014 the Federal Trade Commission had filed an administrative complaint against Ferrellgas, the operator of Blue Rhino, and against AmeriGas, claiming the pair had coordinated that reduction instead of competing over it. Both later settled without admitting wrongdoing. Nothing has changed since: the cages still dispense 15 pounds while the label on the front still reads 20 pound tank.
Break it down by the pound and the picture turns sour quickly. Pay $25 to $30 for 15 pounds at the cage and you are spending roughly $1.80 a pound, but a refill at a hardware store, RV dealer, or U-Haul yard typically costs $3.50 to $4.50 a gallon, so a full 20 pound fill lands near $20 and cuts your true cost to about a dollar a pound. Since propane weighs about 4.2 pounds per gallon, those 5 missing pounds add up to a little more than a gallon, or nearly two hours of cooking on a mid size burner. Identical tank, identical fuel, except a refill lets you keep every pound your money bought.
You can settle this yourself in half a minute with any cylinder. Find the letters TW and a number on the collar, usually 17 to 18 pounds on a steel 20 pounder, which tells you the empty weight. Put the tank on a bathroom scale, subtract that TW number, and the remainder is the propane you are actually bringing home. Try it before your next swap and the shortfall will stare back at you from the scale long before you ever fire up a burner.
The cage does still win at one thing. A refill station legally cannot fill a cylinder more than 12 years past the manufacture date stamped on its collar, whereas an exchange will accept your expired tank and requalify it in house. Use that once for an old cylinder, then refill the fresh tank they give you and you can leave exchange pricing behind for good. [1I2J5]