What is the outside diameter of Poly B pipe?
The straight answer
Poly B is copper tube size: half-inch nominal measures 5/8 inch outside, three-quarter measures 7/8 inch, and one-inch measures 1-1/8 inch. That shared sizing is why rated transition fittings to PEX and copper work.
The longer version
Poly B is CTS, copper tube size: 1/2″ nominal is 0.625″ OD, 3/4″ is 0.875″, and 1″ is 1.125″, the same outside diameters as copper, PEX and PE-RT. That’s why properly rated transition fittings work dimensionally, and why the certification, not the fit, is what matters. The fittings guide has the details.
People also ask
Grounding
This answer summarizes material sourced in full on the chapter pages it links. If the facts change, the chapter changes first and this answer follows.
Published by Poly B Plumbing Guys
This library is maintained by the team that replaces Poly B every day across Alberta and BC. Red Seal certified plumbers, full remove-replace-restore service including drywall and paint, a 25-year warranty, and the completion certificate insurers ask for.
Get your pipes checked →