Concrete Block Calculator — How Many Blocks Do I Need?

Enter the wall’s length and height to estimate the number of standard 8×8×16-inch concrete blocks, mortar joints and a little waste included.

How this calculator works

We figure wall area (length × height) and multiply by about 1.125 standard 8×8×16 blocks per square foot (joints included), then add 5% for cuts and breakage.

What changes how much you need

A standard 8×8×16 CMU covers about 0.89 sq ft of wall — roughly 1.125 blocks per sq ft.
Half and corner blocks change counts at ends and openings.
Plan about 3 bags of mortar per 100 blocks.
Order 5–10% extra for cuts and breakage.

Frequently asked questions

How many concrete blocks per square foot?

About 1.125 standard 8×8×16-inch blocks per square foot of wall, including mortar joints.

How much mortar for concrete block?

Roughly 3 bags of mortar per 100 blocks, depending on joint size and conditions.

What size is a "standard" concrete block?

Nominal 8×8×16 inches (actual 7⅝ each way, to allow for a 3⁄8-inch mortar joint).