Concrete Block Calculator
Calculate how many concrete blocks a wall needs, plus the mortar bags and sand to lay them, with openings deducted.
Formula and figures last reviewed by the Cosyslabs team · how we verify
Inputs
Result
Blocks needed
189
Wall area (net)
160 ft²
- Mortar bags (70 lb)
- 6
- Mortar sand
- 6.75 ft³
- Courses high
- 12
- Waste
- 5%
Waste default: 5% — Five percent covers breakage in transit and cut blocks at openings and corners.
Estimates only. Verify with a licensed contractor or supplier before purchasing. Rough Estimator! is not responsible for shortages, overages, or material variances. See our methodology for formulas and sources.
Formula
Blocks = wall area ÷ 0.889 ft² per block × (1 + waste) · a nominal 8×8×16 block covers 128 in² of wall face including its joint
References
Related tools & materials
Don't forget
- Mortar mix
- Masonry sand
- Rebar
- Grout
- Ladder wire reinforcement
Also useful
Frequently asked questions
A standard 8 × 8 × 16 in block covers 0.889 ft² of wall face including its mortar joint, so divide the wall area by 0.889 — or multiply by 1.125. A 20 × 8 ft wall of 160 ft² takes about 180 blocks before waste.
Ad space
Cite this page
Cosyslabs. (2026). Concrete Block Calculator. Rough Estimator!. https://roughestimator.com/concrete-block-calculator
Embed on your site
Free for any site — attribution appreciated.
<iframe src="https://roughestimator.com/concrete-block-calculator?embed=1" title="Concrete Block Calculator" width="100%" height="640" style="border:0;border-radius:12px" loading="lazy"></iframe>