AAC block calculator

Work out the AAC blocks, thin-set mortar and reinforcement for your walls.

LHlh
Letters on the drawing match the letters next to the inputs.
ft
ft
sq ft
in
More settings
lb
%
$
AAC blocks742 pcs
Volume of blocks24.4 yd³

Shopping list

  • AAC blocks742 pcs
  • Volume of blocks24.4 yd³
  • Thin-set mortar for AAC1,215 lb · 25 bags of 50 lb
  • Bars for bed reinforcement1,008 ft
  • Weight of the bars (8 mm)267 lb

How we got there

Wall area without openings
960 sq ft
Units per area
0.74 pcs/sq ft
Rows of blocks
14 pcs
Reinforced rows
4 pcs

Results are estimates. Always check the coverage printed on the product and your local building code.

Calculated on planicalc.com · https://planicalc.com/us/aac-block-calculator/

How it is calculated

Add up the length of all walls of the same thickness, multiply by the height and subtract the windows and doors. The area divided by the face of one block with its joints gives the number of blocks, plus extra for cutting. Thin-set mortar is counted for the bed and head joints of every block at about 1.5 kg per m² for each millimeter of joint. With joints of 5/16 in or more the calculator counts ordinary mortar instead. The first course and every fourth course get bars in routed chases: two bars in walls 8 in or thicker, one in thinner walls. The wall length, height and openings are remembered and filled in for the ICF calculator, and the wall length for the footing calculator too. The wall length, height and openings are remembered and filled in for the ICF calculator, and the wall length for the footing calculator too.

FormulaBlocks = (L × H − openings) ÷ ((l + joint) × (h + joint)) × (1 + extra)Volume = blocks × l × h × tMortar = blocks × (l + h) × t × joint × 1.5 kg/m² per mmReinforcement = reinforced courses × L × bars × 1.05

Example

Walls 120 ft long and 9 ft high with 120 sq ft of openings have 960 sq ft of masonry. With 24 × 8 in blocks 8 in thick and 1/8 in joints you need 742 blocks including 5 % extra, about 1,214 lb of thin-set mortar — 25 bags of 50 lb — and 1,008 ft of bar for 4 reinforced courses.

Tips from practice

  • Set the first course on a level bed of regular mortar over a moisture barrier: any error shows in every course above.
  • Use a notched trowel the width of the block so the thin-set joint stays about 1/8 in thick.
  • Over windows and doors use lintels or U-blocks with a grouted bond beam, and run a bond beam under floors and the roof.
  • Before you lay the blocks, decide where the consumer unit, sockets and vent ducts go: chasing aerated concrete is easy, but vent openings are best left as you build.
  • Before you lay the blocks, decide where the electrical panel, outlets and vent ducts go: routing AAC is easy, but vent openings are best left as you build.

Questions and answers

How many AAC blocks per square foot?

A 24 × 8 in block covers 1.33 sq ft, so with thin joints you need about 0.74 blocks per square foot, or 74 per 100 sq ft.

How much thin-set mortar per AAC block?

With 1/16–1/8 in joints, about 1.2–1.8 lb for an 8 in thick 24 × 8 in block. The calculator counts it from the block size and joint thickness.

Is AAC strong enough for a house?

Yes, AAC is used for one- and two-story load-bearing walls and is common in Florida and the Southeast. It needs bond beams, proper lintels and an engineered design under US codes.

Found a mistake in a formula? Write to [email protected]