Calculators / Concrete Block
Concrete Block Calculator
To calculate concrete blocks, enter your wall length and height; this tool returns the number of standard CMU blocks you need plus a cost estimate. A standard 8×8×16 in block covers about 0.89 sq ft of wall, so you need roughly 1.125 blocks per square foot once the mortar joint is included.
Real math, not AI guesses.
You need
189 blocks
Estimated cost
~$378
- Wall area
- 160 sq ft
- With 5% waste
- 168 sq ft
- Blocks (16×8 in face)
- 189
Estimate only — actual quantities and prices vary by region and supplier. Verify with a professional before purchasing. Default price is a national average (as of 2026-06); edit it to match your supplier.
How to calculate concrete blocks
The formula: blocks = ceil( wall area × (1 + waste) ÷ block face area )
- Measure the wall length and height in feet and multiply for the wall area.
- A standard block face is 16×8 in including the mortar joint — about 0.89 sq ft, or roughly 1.125 blocks per sq ft.
- Add about 5% for cuts and breakage.
- Divide the wall area by the block face area and round up. Subtract large openings (doors, windows) for a tighter count.
Prices shown are national averages (as of 2026-06) and vary by region, brand, and supplier. They are estimates, not quotes.
How much do concrete blocks cost?
Standard 8×8×16 in concrete blocks (CMU) cost about $1.50–$3.00 each, so the block for a 20×8 ft wall (≈180 blocks) runs roughly $270–$540 in materials, plus mortar and sand. Built and laid by a mason, a concrete block wall typically costs $10–$20 per square foot installed — including blocks, mortar, reinforcement, and labor — about $1,600–$3,200 for that same 160 sq ft wall.
What drives the cost
- Block type — standard gray CMU is cheapest; split-face, decorative, and 12 in blocks cost more.
- Mortar, rebar, and grout fill add to materials beyond the blocks themselves.
- Labor is most of an installed wall — masonry is skilled, slow work.
- Wall height, corners, and openings raise the per-block labor.
- Your region, and whether the wall is load-bearing or a foundation.
DIY vs. hiring a pro
Laying block yourself saves the labor — most of the installed cost — and a short garden or planter wall is a reasonable DIY project. But a level, plumb, properly tied wall takes practice, and load-bearing or foundation walls usually need a mason (and often an inspection). Buy about 5% extra for cuts, and use a level and line blocks to keep courses straight.
Installed and labor figures are national-average ranges, not quotes — get a few local estimates for your project.
Concrete Block FAQ
How many concrete blocks do I need for a wall?+
Multiply wall length × height for the area, then about 1.125 standard blocks per square foot. A 20×8 ft wall (160 sq ft) needs roughly 180 blocks before subtracting openings — this tool adds ~5% for breakage, so it suggests about 190.
How many blocks are in a square foot?+
About 1.125 standard 8×8×16 in blocks per square foot of wall once the 3/8 in mortar joint is included. So 100 sq ft of wall is about 113 blocks.
How much mortar do I need for concrete block?+
Plan on about 3 bags of mortar (70 lb) per 100 blocks — roughly one bag per 33 blocks — plus sand. Add more for wider joints or rough conditions.
How much does a concrete block wall cost?+
About $10–$20 per square foot installed, including blocks, mortar, and labor. A 20×8 ft wall (160 sq ft) runs roughly $1,600–$3,200 by a mason, or about $270–$540 in block materials if you lay it yourself.
Are concrete blocks cheaper than poured concrete?+
For walls, block is often cheaper to DIY and easier to build in stages; poured concrete can be stronger and faster for a pro with forms. The cheaper option depends on wall size, height, and local labor rates.