Concrete Block Calculator

Enter wall dimensions, openings, actual CMU face size and mortar joint. See blocks to order, packs, optional mortar bags and material cost without relying on a fixed supplier.

Enter measurements below. Results update as you type, and optional prices can be added before sharing the estimate.

01 — Wall measurements

Measure the wall face

Wall length

Wall height

Doors/windows total area

sq ft

Subtract all planned openings as one combined area.

02 — Real product dimensions

Use the actual face size from your supplier

The defaults are a standard US CMU face: 15⅝ × 7⅝ inches, before the mortar joint. Units are counted from the exposed face, not the block depth.

Block face length

Block face height

Mortar joint thickness

03 — Purchase quantities

Cut/breakage allowance

Typical planning allowances depend on wall pattern and job conditions.

Units per pack or pallet

pcs

Use 1 if buying loose units.

Units laid per mortar bag

pcs

Enter the yield printed on your chosen mortar product; 0 skips mortar estimation.

Optional local material prices

Price per brick/block

Price per mortar bag

Estimating wall-face units only. Reinforcement, structural cores/grout, corners, bond patterns, lintels, footing quantities, drainage and permits are excluded. Have a qualified professional check structural work.

Results update as you enter dimensions.

The calculation

Blocks = net wall area ÷ installed block face coverage

Blocks before waste = (wall length × wall height − openings) ÷ ((actual face length + mortar joint) × (actual face height + mortar joint))

All measurements are converted to the same units before division; block face coverage includes joints on both horizontal and vertical dimensions.
Typical US 8 × 16 inch nominal CMU face uses an actual 7⅝ × 15⅝ inch face with a ⅜ inch joint; always adjust for your product.
Waste is added before rounding to whole units. Full packs use the entered supplier pack size.
Mortar bags are estimated only when you enter the actual blocks-per-bag product yield.
Do not treat the wall-face count as structural engineering or a masonry specification.

Quick examples

20 ft × 8 ft wall, no openings160 sq ft gross area

Nominal 8 × 16 in CMU face180 blocks before waste

Add 10% allowance198 blocks (rounded whole units)

24 blocks per pallet9 full pallets if ordering only full pallets

Examples are planning checks. Product-label coverage and whole pack sizes control the final purchase quantity.

Verified references

Check the exact product data before ordering

Omni Calculator — Concrete Block Calculator

Reference for wall face/unit count and material scope; editable actual product dimensions control this calculator.

Open source

Inch Calculator — Block Mortar Calculator

Reference for variable mortar quantity and the importance of joint and product assumptions.

Open source

Plan manufactured or thin-stone veneer quantities with editable product coverage.

Open calculator

Common questions

Understand the result before purchasing

01How many concrete blocks do I need for a wall?+

Multiply the wall length by height, subtract the total area of openings, then divide by the exposed face area of one block plus its mortar joints. Add waste and round up to whole blocks. This calculator performs those steps.

02How many 8 by 16 CMU blocks are in one square foot?+

Using a nominal block face of 8 by 16 inches including standard joints, one block covers 128/144 square feet, so the estimating rate is about 1.125 blocks per square foot before waste.

03Should I use actual or nominal block sizes?+

Enter the actual face measurements of the product, not its nominal label size. The calculator adds the entered joint thickness to the face length and height to estimate installed coverage.

04How do I allow for doors and windows?+

Enter the combined face area of door and window openings. It is deducted before applying the selected breakage/cutting allowance. Do not subtract more than the wall face area.

05Can I calculate mortar bags?+

Yes, enter how many blocks your specific mortar bag can lay based on your mortar product and joint assumptions. Bag count is rounded up. If you leave that value at zero, mortar bags are not estimated.

06Does this calculate structural concrete block fill?+

No. This is a wall-face unit-count and mortar purchasing estimator. It does not calculate reinforced cores, bond beams, footing quantities, grouting, lintels, structural design, or local building-code requirements.

07How can I use the total for a price quote?+

Enter the actual supplier price per block and optionally per mortar bag. The displayed material total excludes deliveries, labor, waste disposal, reinforcement, tax and contractor scope.