How many gallons does an 11 lb propane cylinder hold?

An 11 lb propane cylinder holds approximately 2.5 US gallons of propane. This is based on the fact that propane has a specific gravity of about 0.504 relative to water, meaning it is less dense than water. The general rule for converting pounds of propane to gallons is based on the understanding that one gallon of propane weighs roughly 4.24 pounds. Therefore, to find the capacity of an 11 lb cylinder in gallons, you can divide the weight of the propane by the weight per gallon:

11 lb ÷ 4.24 lb/gallon ≈ 2.6 gallons.

However, due to standard cylinder design and safety considerations, the practical volume is closer to 2.5 gallons. Therefore, considering both theoretical and practical aspects, 2.5 US gallons is the most accurate figure for the contents of an 11 lb propane cylinder.