Construction Calculator - Concrete and Masonry

Concrete and Cinder Block Calculator

Estimate concrete blocks for walls by wall size and block face dimensions.

Reviewed: August 26, 2026

Calculate Concrete and Cinder Block

For the Concrete and Cinder Block Calculator, enter wall length, wall height, unit face length, unit face height, waste allowance, and unit price. It divides wall face area by the installed unit-face module, applies allowance, and rounds up to whole masonry units with optional unit cost.

Construction measuring tools arranged beside a residential building project

Formula used

Units = ceil([wall area ÷ installed unit-face module] × [1 + waste ÷ 100])

Concrete and Cinder Block Calculator measurement plan showing Wall length feet, Wall height feet, Unit face length inches

Worked concrete and cinder block example

Concrete and Cinder Block Calculator example: 30.6 ft × 4.59 ft = 140.45 ft². A 16-in × 8-in face module occupies 0.8889 ft², producing 171 units after 8% allowance and whole-unit rounding.

Reading the unit or bag result

Round to whole units and separate specialty shapes such as bond-beam, lintel, corner, and cap units before ordering.

Face-area count is only the first masonry takeoff

The unit count uses installed face dimensions, so the length and height inputs should represent the block-plus-joint module when joints are present. Corners, bond beams, pilasters, half units, control joints, lintels, and cut units need separate review. Mortar, grout fill, reinforcement, and cap units are not included in the block count.

Details the area formula cannot see

Half units, corners, bond patterns, control joints, pilasters, openings, and units cut at returns change the count from a simple face-area division.

Questions specific to this calculation

Should block face dimensions include the mortar joint?

Enter wall length and height, then enter the nominal face module occupied by one unit in the wall, including the intended mortar-joint module where appropriate.