Concrete Block Calculator
Calculates standard nominal 8"×8"×16" concrete masonry units (CMU), Type S masonry mortar bags, horizontal ladder wire, and core-fill grout concrete based on wall length and height.
Formula
Blocks = (Wall Area in Sq Ft × 1.125) × (1 + Waste %); Mortar Bags = Ceil(Blocks ÷ 33)
1. Wall Area = Length ft × Height ft 2. Nominal Block Area = (16 in × 8 in) ÷ 144 = 0.888 sq ft per block (1.125 blocks per sq ft) 3. Base Blocks = Wall Area × 1.125 4. Total Blocks with Waste = Ceil(Base Blocks × (1 + Waste %)) 5. Type S Mortar Bags (80 lb) = Ceil(Total Blocks ÷ 33 blocks/bag) 6. Core Grout Volume = Blocks × (Fill Factor ? 0.012 cu yd/block : 0)
Inputs
- Wall Length
- Wall Height
- Core Fill Grouting
Worked example
Building an 8x8x16 CMU retaining wall with mortar and core fill every 32 inches.
Outcome: Wall area is 180 sq ft. Requires 180 × 1.125 = 202.5 blocks. Adding 8% waste gives 219 blocks (ordered as 2 pallets of 108 plus 3 singles). Type S mortar: 7 bags (80 lb). Rebar: 22 ten-foot #4 bars.
How many concrete blocks are on a standard pallet?
A standard pallet of standard 8x8x16 CMU contains 108 blocks (or 120 blocks in some regional distributors), weighing approximately 3,800 to 4,100 lbs.