What is the standard thickness of most interior passage doors?

The standard thickness for most interior passage doors is 1-3/8 inches. This measurement is commonly used in residential construction to provide a balance of durability, cost, and insulation properties. Doors of this thickness are typically adequate for providing privacy and sound attenuation between rooms, which is often required in interior spaces.

While there are thicker doors available, such as 1-3/4 inches for exterior use or specialized applications, 1-3/8 inches is the most prevalent size for standard interior doors. This size allows easy handling and installation while still maintaining a sturdy feel.

The other measurements, such as 1-1/2 inches and 1-1/4 inches, are not standard for most interior passage doors, as they do not meet the common requirements for stability and performance in typical residential applications.