I need the formula to get 2 pvc measurements wihtout using a tapemeasure

Alternative formulas instead of a tapemeasure.
You can use a yard stick or a stick rule or a laser or a sonic measuring instrument.
Actually you have not posted enough information on your request.

What do you want? Stuff like the diameter of 3/4'' PVC? You might find it on a website of a manufacturer, perhaps Genova. The ASTM or NSF may have specifications.