Masonry: Block Courses in a Wall

All versions

A block wall goes up in courses, and each standard CMU with its mortar joint adds eight inches of height. Divide the wall height by the course height and you know how many rows the wall stands.

Quick formula: Wall height divided by the course height:

=ROUNDDOWN(B2/C2,0)

A 48-inch wall in 8-inch courses is six rows of block.

Functions used (tap for the full reference guide):

ROUNDDOWN

The example

Three walls, each with a finished height in inches and the course height of the block being used.

	A	B	C	D
1	Wall	Height in	Course in	Courses
2	Garden wall	32	8	4
3	Retaining	48	8	6
4	Foundation	96	8	12

The formula

Wall height over course height gives the number of rows:

=ROUNDDOWN(B2/C2,0) // wall height / course height, rounded down to whole courses

How it works

Two inputs:

B2 is the finished wall height in inches.
C2 is the course height — a standard 8-inch CMU is 7-5/8 inches of block plus a 3/8-inch mortar joint, which comes to 8.
ROUNDDOWN(...,0) rounds down, because a partial course is not a full row of block.
Multiply the courses by the blocks per row (wall length over 16 inches) for the total block count.

Half-height (4-inch) block and cap units change the course height — keep it in its own cell so you can switch block types.

Try it: interactive demo

Interactive

Enter the wall height and the course height, in inches.

Wall height (in)

Course height (in)

Variations

Blocks in the wall

Courses times the blocks per row (length / 16 in) is the total count.

=ROUNDDOWN(B2/C2,0)*ROUNDUP(D2/16,0)

Half-height cap course

Use a 4-inch course height for a cap or veneer row.

=ROUNDDOWN(B2/4,0)

Pitfalls & errors

Use the nominal 8-inch course, not the 7-5/8-inch block face. The mortar joint is part of the course height — dividing by the bare block would overstate the row count.

If the wall height is not a clean multiple of the course, you will need a cut course or a different footing depth. A non-whole result is a heads-up to check the elevation.

Practice workbook

📊

Download the free Masonry: Block Courses in a Wall practice workbook

Edit the yellow wall-height and course-height cells; the course count recalculates.

Frequently asked questions

Why is the course height 8 inches?

A standard concrete block is 7-5/8 inches tall, and a 3/8-inch mortar joint brings each course to a nominal 8 inches. Always divide by the nominal course, mortar included.

How do I get the total block count?

Multiply the courses by the blocks per row. A row is the wall length divided by 16 inches (the nominal length of one block), rounded up.

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Function references: ROUNDDOWN