Concrete Block Fill Calculator

cu in
Standard 8×8×16 CMU: ~180 cu in per block (two cores).
%
Construction

Calculate the volume of concrete fill needed to grout and fill concrete masonry unit (CMU) block cores.

Formula

Volume = blocks × core volume × fill rate ÷ 1728 (to cu ft)
  • Standard 8×8×16 CMU has two cores totaling ~180 cu in.
  • Partially filled walls (every other core) reduce fill by 50%.

200 blocks, 180 cu in cores, 100% fill

Inputs
  • Number of Blocks: 200
  • Core Volume per Block: 180 cu in
  • Percentage of Cores Filled: 100 %

200×180 = 36,000 cu in = 20.83 cu ft = 0.77 cu yd.

Frequently asked questions

Why fill CMU cores?
Filling cores with grout and reinforcing with rebar significantly increases the wall's strength and seismic resistance.