Rebar Calculator
Rebar for a slab.
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Construction
Block Wall Calculator
Find how many concrete blocks a wall needs.
Blocks needed
—
Incl. 5% waste.
| Wall area | — |
|---|---|
| Blocks (no waste) | — |
| Length | — |
| Height | — |
Show our math
Enter your figures above to see the step-by-step working.
Everything computed client-sideEverything computed client-side — nothing leaves this page
How the Block Wall Calculator Works
A standard 8×8×16-inch concrete block covers about 0.89 square feet of wall face, so a wall takes roughly 1.125 blocks per square foot. Multiply the wall area by that and add about 5% for waste and breakage. A 20×8 ft wall needs about 189 blocks.
Deduct large openings, and remember you’ll also need mortar — about three 80-lb bags of mortar mix per 100 blocks.
blocks = wall area × 1.125 × 1.05 (waste)
Frequently Asked Questions
How many blocks per square foot?
About 1.125 standard 8×8×16-inch blocks per square foot of wall.
How many blocks for a 20x8 wall?
Around 189 including a 5% waste allowance.
How much mortar do I need?
Roughly three 80-lb bags of mortar mix per 100 blocks.
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