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Concrete Block Sizes and Dimensions

Nominal and actual sizes of common concrete masonry units (CMU), with how much wall each block covers.

Common CMU sizes
Nominal size (W × H × L)Actual sizeActual size (mm)Typical useAction
4 × 8 × 16 in3 5/8 × 7 5/8 × 15 5/8 in92 × 194 × 397Non-load-bearing partitions, veneers and screen walls.
6 × 8 × 16 in5 5/8 × 7 5/8 × 15 5/8 in143 × 194 × 397Interior partitions and light walls.
8 × 8 × 16 in7 5/8 × 7 5/8 × 15 5/8 in194 × 194 × 397The most common size: foundation, basement and exterior walls.
10 × 8 × 16 in9 5/8 × 7 5/8 × 15 5/8 in244 × 194 × 397Taller or more heavily loaded walls, where specified.
12 × 8 × 16 in11 5/8 × 7 5/8 × 15 5/8 in295 × 194 × 397Retaining and heavily loaded walls, where specified.

Nominal vs actual dimensions

A block's nominal size includes one 3/8 in mortar joint. The block itself is made 3/8 in smaller in each face dimension, so an 8 × 8 × 16 in block measures about 7 5/8 × 7 5/8 × 15 5/8 in. Laid with a 3/8 in joint, it fills exactly 8 × 16 in of wall.

Face coverage

All the sizes above share a nominal 8 × 16 in face (128 sq in), so each covers the same wall area: about 1.125 blocks per square foot. Width (thickness) changes the wall, not the block count. A metric 400 × 200 mm nominal face covers 0.08 m², or 12.5 blocks per m².

Weights and pallet quantities

Block weight and pallet counts depend on the manufacturer, the concrete density (lightweight, medium or normal weight), and the block's shape. They are not shown here as universal figures. Check the manufacturer's data sheet for the product you plan to buy.

Sources

Dimensions follow the standard modular convention. Individual products vary: confirm sizes, weights and availability with your supplier or the manufacturer's data sheet.