Which unit of measurement is commonly used to express pipe diameter?

In the context of plumbing and piping, inches are the most commonly used unit of measurement for expressing pipe diameter, particularly in North America. This standardization stems from traditional practices and the historical use of the imperial measurement system in the region. Pipe diameters for various types of piping, such as PVC, copper, and steel, are typically specified in inches, facilitating easier communication and consistency among professionals in the field.

While centimeters and millimeters are used in some regions or specific applications—especially for smaller fittings or precise measurements within metric-converted specifications—inches remain the prevalent unit for general pipe sizing due to their widespread acceptance in construction and plumbing standards. Feet, being a larger unit of measure, are usually used for lengths rather than diameter, making them less appropriate for this specific context of measuring pipe dimensions.