Tape measure used as PI tape

Can this device be used as pi tape? That is wrapped around the circumference of a pipe to calculate the diameter? Normally you do this measurement and divide by 3.14 to get the diameter.
C = 2 x (3.14) x Radius
Or C= πD or C/π=D
Pipe circumference divided by 3.14 = diameter

Hello, while it could, generally metal tape measures are less ideal for measuring round objects (since they need to be bent).

Do you do this process now using a normal tape measure? If so it would be great to hear about how you do this now and what kind/diameter of pipes you are measuring!


I currently use pipe tape, which is flat, unlike the curved tape measure that most people use. The hook on the end of a curve tape measure also gives an error in actual circumference. I usually measure pipes from 4-12 inches in diameter to verify schedule size and to order the correct flange when installing valves or diverters based on the pressure or vacuum the system has. I’ve also used pi tape to measure diameters of plenums and turbine housings in auxiliary power units up to 24” diameter.