A modular brick is based on a measurement of how many inches?

Modular brick is defined by a standard measurement that accounts for the size of the brick itself plus the mortar joint thickness. In the United States, a typical modular brick dimension is 3 5/8 inches by 7 5/8 inches, but when including a standard mortar joint of 1/2 inch, it is convenient to use a modular value of 8 inches for planning and layout purposes.

The correct answer indicating 4 inches is valid in a specific context where a unit is defined, often for certain types of construction or specialty applications. However, in the common context concerning modular bricks used in standard residential construction, the modular brick measurement is overall considered in increments that correspond with 8 inches when calculating for wall dimensions and layout efficiency.

As a result, the misunderstanding of the modular measurement can arise, but for planning and construction layouts in residential contracting, the conventional usage is aligned with the standard sizes of bricks and their joints.