The title implies that the tape does the work, so you don’t have to. This is true. All
you have to do is wrap the tape around the pipe circumference. Then the markings on the tape show you the diameter. It does this because the markings are spread out by a factor of pi (3.14159). So you don’t have to measure the circumference and divide by pi.
The accuracy of a pocket size Pipe Diameter Tape Measure is usually 100th of an inch diameter. That’s a pretty good resolution. They also come in metric units. Their accuracy is in millimeters diameter.
