It’s important to remember that when buying fittings for plumbing and heating systems, copper pipe sizing refers to the listed size of the pipe which is approximately the inner diameter.
For example, a ½ inch Copper fitting doesn’t actually measure ½ inch. It simply fits over the ½ copper pipe. A ½ inch street fitting will have an inside diameter of 1/2 inch, as it is the same size as the pipe, and it will fit inside of another fitting.
On our website we abbreviate these as C fittings for pipe connections and FTG fittings for connections to other fittings.
It can get confusing when buying online, but just keep the inner diameter in mind.
