What are the actual dimensions of a 12" x 12" glass block unit?

The actual dimensions of a 12" x 12" glass block unit are typically 3 7/8" x 11 3/4" x 11 3/4". This measurement reflects the nominal size, which is often different from the actual manufactured dimensions due to the manufacturing process. The nominal measurements are used for identification and marketing, while the actual dimensions account for the material and any production tolerances.

In this case, while the nominal label suggests a square unit of 12" each side, the actual size takes into consideration the thickness of the material and variations in production, leading to the specified measurements. This is an important concept in carpentry and construction, as understanding the difference between nominal and actual dimensions is crucial for accurate planning and fitting in building projects.