Concrete Block Calculator
How many blocks do you need? Enter your wall size.
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Wall area—
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How this calculator works
A standard 8×16 inch concrete block covers about 0.89 sq ft of wall with mortar, so it takes roughly 1.125 blocks per square foot. The calculator applies that rate and adds 5% for waste.
Worked example — a 20 ft × 8 ft wall:
160 sq ft × 1.125 × 1.05 = 189 blocks.
Blocks per square foot
The 1.125 figure assumes the common 8×8×16 inch block. Half-height or specialty blocks will change the count.
Frequently asked questions
How many concrete blocks per square foot?
About 1.125 blocks per square foot for standard 8×16 inch units with mortar joints.
How many blocks for a 20×8 wall?
Roughly 189 blocks including a 5% waste allowance.
Planning a concrete or masonry project
Material estimates are only one part of a masonry job. Check the product yield on the bag or supplier quote, allow for the shape of the site, and confirm delivery minimums before ordering. For structural work, follow local building requirements and get advice from a qualified professional.
How to use this estimate
- Measure the project in the units shown and recheck your measurements before ordering.
- Use the waste allowance as a planning buffer, not as a substitute for a detailed material takeoff.
- Compare the result with the package yield, coverage, or weight listed by your supplier.
- Prices are user-entered estimates and may change by location, product, delivery, and season.
Accuracy and limitations
Calculapedia provides educational planning estimates. It does not inspect your site, select products, guarantee quantities, or replace a contractor, engineer, architect, building official, or supplier. Confirm the final quantity and any safety or code requirements before buying or building.