"Steve B" wrote in message

Now I'm really confused. I just went and looked at my tank. On the top,
it is stamped TW 17.0 , which I would take to mean that the tare weight is
17#. That feels right, about like a bowling ball. This tank is about knee
high, and in liquid would say it would hold around five gallons just
looking at it. However, full, it weighs a lot. How ARE these things
rated? In pounds of liquid in side? In gallons? When I go get them
filled, they charge me by the gallon. Help me out, please. Is a 17#
empty tank called a 20# because it's approximately twenty pounds empty?
Propane weighs 4.24# per gallon, so that's about 21 pounds for five
gallons. Is that a rounded number, too?

It will take 20 pounds of liquid. Most fill the tank on a scale and stop
when it hits 37# total. Most places also charge a flat fee, not by the
gallon. Right now I'm paying $9.99 a fill up.