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The terms get used interchangeably, but they’re not technically the same. Concrete blocks (CMUs) are made from cement, sand, and gravel — they’re heavier, stronger, and used in structural construction. Cinder blocks were originally made with cinders (the ash byproduct from burning coal), which made them lighter but weaker. True cinder blocks are rarely produced today, so almost every “cinder block” you’ll see at a yard is actually a concrete block.

CMU stands for Concrete Masonry Unit. It’s the technical industry term for what most people call a concrete block. If a spec sheet, plan, or building code references CMUs, they’re talking about standard concrete blocks — the size, grade, and strength will be specified by ASTM standards (typically ASTM C90 for load-bearing units).

Plan on roughly 3 standard 80-pound bags of mortar mix per 100 concrete blocks, assuming a standard 8x8x16 block and 3/8″ mortar joints. A typical mason will mix one bag at a time to keep the mud workable. Always order 5–10% extra to cover spillage, joint repointing, and tooling losses.

Add 5–10% to your block count to cover breakage, cuts at corners and openings, and the occasional damaged unit straight from the pallet. Walls with lots of windows, doors, or angled corners should lean closer to 10%. Returning excess blocks is usually cheaper than running short — most yards will take back full pallets, but partial pallets often come with a restocking fee.

Most U.S. contractors charge $10–$20 per square foot for installed concrete block walls, including blocks, mortar, rebar, and labor. Block-only material cost runs about $1.50–$3 per block depending on size, grade, and region. Reinforced walls (filled cells, rebar, bond beams) sit at the higher end. Decorative split-face or architectural CMU can push pricing well above $25 per square foot.

A standard 8x8x16 concrete block weighs around 38 pounds. Lightweight CMUs (made with expanded shale or pumice aggregate) come in around 28 pounds. Solid concrete blocks of the same size can hit 50+ pounds. Weight matters for load calculations, scaffolding, and how many blocks your mason can comfortably lay in a shift.

An experienced mason typically lays 90–120 standard concrete blocks per 8-hour day on straight wall runs with no complications. With a tender (helper) keeping mortar and blocks staged, that number can climb to 150–180. Rate drops fast for jobs with lots of corners, openings, or rebar/grout work. Most contractors estimate labor at the lower end to stay protected on bid day.