Concrete Block Calculator
Enter a wall length and height, or a total wall area, and get the full material list: concrete blocks, mortar, core-fill grout, and an optional rebar estimate, plus a 2026 cost. It works for 4, 6, 8, 10, and 12 inch block, and it is free to use with no signup.
Add up the doors and windows you want to leave out, in square feet. Small openings are often left in and let the cut blocks cover waste.
Nominal width. Every size uses the same 8″ × 16″ face, so the block count is the same; width sets the grout, weight, and price. 8″ is the standard structural block.
5% is the standard allowance for cuts and breakage; use 10% for a cut-up wall with lots of corners and openings.
Leave on None for a plain wall. Pick the spacing of the filled cells to add core-fill grout, or All cells for a fully solid-grouted wall. Your engineer or plans set the real spacing.
Illustration, not to scale
Illustration, not to scale
Concrete blocks (with 5% waste)
189blocksof 8″
160 sq ft wall = 160 sq ft face.
A material list to price and order from, not a substitute for measuring or the structural drawings. Field-measure or take off the plan, and follow the stamped rebar schedule, before you buy.
You sized one wall by hand?
Measure every block wall off your plan instead. Easy Takeoffs takes off wall length and height straight from the PDF to scale, so your block, mortar, grout, and rebar come from the print. 14-day trial, no card.
How much does a concrete block wall cost?
A concrete block wall runs about $15 to $30 per square foot installed in 2026, so a plain 8 inch wall is around $15 to $20 a square foot and a grouted, reinforced wall $18 to $24. Materials alone are far less. A standard 8 inch block is about $1.50 to $3.00 each, an 80 lb bag of mortar $9 to $18, and core-fill grout $150 to $250 a cubic yard delivered. Labor is the larger share. Prices vary by region, so treat these as a starting point.
What a block wall costs (2026 US)
| Item | Typical cost |
|---|---|
| Standard 8 in block, single unit | $1.50 to $3.00 each |
| 8 in block by the pallet | $1.25 to $2.00 each |
| 4 in and 6 in block | $1.20 to $2.50 each |
| 10 in and 12 in block | $2.50 to $5.50 each |
| Mortar, 80 lb bag (Type S premixed) | $9 to $18 |
| Core-fill grout, ready-mix delivered | $150 to $250 per cu yd |
| Rebar, #4 to #5 (material) | $0.40 to $1.05 per ft |
| Installed, plain wall | $15 to $20 per sq ft |
| Installed, grouted and reinforced | $18 to $24 per sq ft |
2026 US figures from HomeGuide, Angi, and Homewyse (2026) plus retail listings, with grout from ready-mix references. These are homeowner-facing aggregator ranges, not bid-grade. Region alone swings prices up to about 30 percent, and labor is roughly half to two thirds of an installed price.
What a block wall costs by size (installed, 2026)
| Wall face area | Blocks (8 in) | Materials | Installed |
|---|---|---|---|
| 100 sq ft | ~119 | $300 to $900 | $1,500 to $3,000 |
| 200 sq ft | ~237 | $600 to $1,800 | $3,000 to $6,000 |
| 500 sq ft | ~591 | $1,500 to $4,500 | $7,500 to $15,000 |
| 1,000 sq ft | ~1,182 | $3,000 to $9,000 | $15,000 to $30,000 |
By wall FACE area (length × height), not floor area, for 8 inch block at 5 percent waste. The low end is a plain wall (block and mortar); the high end adds grout and rebar for a reinforced wall. Installed is material plus labor. 2026 aggregator ranges, regional.
What materials do you need to build a block wall?
A concrete block wall takes more than the block. For every wall you also need mortar to bed the units, and on a reinforced wall, grout to fill the cells around the steel, plus vertical rebar and horizontal joint reinforcement. The calculator totals each one from your wall, using standard coverage: 1.125 blocks per square foot, about one 80 lb bag of mortar per 12 blocks, and a grout volume that depends on the block width and how many cells you fill.
Block-wall materials at a glance
| Material | How it is sold | Coverage |
|---|---|---|
| Concrete block | By the unit or pallet | 1.125 per sq ft of wall (112.5 per 100 sq ft) |
| Mortar | 80 lb premixed bag | About 12 to 13 block per bag (~9 bags per 100) |
| Core-fill grout | Ready-mix (cu yd) or 80 lb bag | By wall area and cell spacing (see the grout table) |
| Vertical rebar | 20 ft bars, #4 or #5 | One per grouted cell, plus laps |
| Joint reinforcement | 9-gage ladder wire, 10 to 12 ft | Every other course (16 in) |
Coverage from block-industry estimating data (Inch Calculator, Fairbanks, Westbrook) and QUIKRETE bag yields, set to the safe end so you never run short. Mortar assumes face-shell bedding at 3/8 inch joints. Grout and steel apply only to reinforced walls, and their amounts come from the structural plans.
How do you measure a wall for concrete block?
You measure a block wall by its face: length times height. Multiply the wall length by its height for the gross area, subtract the door and window openings, and that net area is what the block, mortar, and grout all come from. For the block count it does not matter how wide the block is, since every size shares the same 8 by 16 inch face.
- 1
Measure each wall length and height in feet, and multiply them for the face area: length × height.
- 2
Subtract the door and window openings you want to leave out, in square feet. Small openings are often left in so the cut block covers waste.
- 3
Multiply the net wall area by 1.125 to get the block count, add 5 to 10 percent for waste, and round up. Every block width uses the same count.
- 4
Figure about one 80 lb bag of mortar per 12 block. On a reinforced wall, add core-fill grout for the filled cells and the rebar from your structural plans.
How do you calculate concrete blocks?
Concrete block comes down to wall area. Multiply the wall length by its height, subtract the openings, and multiply by 1.125 to get the block count, because one standard block covers eight ninths of a square foot of wall. The mortar, grout, and rebar all follow from that same wall. Here is the exact math, with a worked example.
- Wall area
- length × height, minus any door and window openings
- Blocks
- wall area × 1.125, then add 5 to 10% for waste and round up (a block covers an 8 in × 16 in face, any width)
- Mortar
- about one 80 lb bag of premixed mortar per 12 blocks, roughly 9 bags per 100 block at 3/8 in joints
- Grout
- core-fill by wall area and cell spacing: an 8 in wall is about 0.43 cu yd per 100 sq ft at 32 in o.c., up to 1.1 cu yd fully solid
- Vertical rebar
- one bar per cell spacing along the length, each the wall height plus a lap; size and spacing set by the engineer
Ordering adjustments
Order to the waste allowance, not the bare count: 5 percent for a straight wall, 10 percent for a cut-up wall with many corners and openings. Round mortar up to whole bags and grout up to the next quarter yard. The block count is the same for every width because they share the 8 by 16 inch face; the width only changes the grout volume, the weight, and the price. Rebar size, spacing, and laps come from the stamped structural plans, not a rule of thumb.
Worked example
A 20 ft long, 8 ft high wall of 8 in block, one 3 by 7 ft door, 5% waste
- Wall area: 20 × 8 = 160 sq ft
- Door: 3 × 7 = 21 sq ft, so net wall = 160 − 21 = 139 sq ft
- Blocks: 139 × 1.125 = 156.4, add 5% waste and round up = 165
- Mortar: 156.4 ÷ 12 block per bag = 13.0, round up to 14 bags of 80 lb
- Grout at 32 in o.c. (8 in block): 139 ÷ 100 × 11.6 cu ft × 1.05 = about 17 cu ft, or 0.6 cu yd
CMU Block reference tables
Concrete block needed for common walls
| Wall (8 ft high) | Face area | Blocks (8 in) |
|---|---|---|
| 10 ft long | 80 sq ft | 95 |
| 20 ft long | 160 sq ft | 189 |
| 30 ft long | 240 sq ft | 284 |
| 40 ft long | 320 sq ft | 378 |
| 50 ft long | 400 sq ft | 473 |
| 100 ft long | 800 sq ft | 945 |
Walls 8 ft high of standard block, with a 5 percent waste allowance, exactly as the calculator computes them: blocks = length × 8 × 1.125 × 1.05, rounded up. Every block width gives the same count. Change the height or add openings above and the numbers update.
Concrete block sizes and weight
| Nominal size | Actual size | Weight |
|---|---|---|
| 4 × 8 × 16 in | 3-5/8 × 7-5/8 × 15-5/8 | About 28 lb |
| 6 × 8 × 16 in | 5-5/8 × 7-5/8 × 15-5/8 | About 30 lb |
| 8 × 8 × 16 in | 7-5/8 × 7-5/8 × 15-5/8 | About 38 lb |
| 10 × 8 × 16 in | 9-5/8 × 7-5/8 × 15-5/8 | About 43 lb |
| 12 × 8 × 16 in | 11-5/8 × 7-5/8 × 15-5/8 | About 52 lb |
Standard hollow units. US block is cast 3/8 inch under nominal, so the unit plus one mortar joint equals the nominal 8 by 16 inch module. Weights are for normal-weight block; lightweight units run about 25 to 30 percent less (a standard 8 inch is about 26 to 28 lb). Confirm the exact weight on your supplier spec sheet.
Core-fill grout per 100 sq ft of wall
| Block width | All cells | 16 in o.c. | 24 in o.c. | 32 in o.c. | 48 in o.c. |
|---|---|---|---|---|---|
| 6 in | 25.1 | 14.9 | 11.3 | 9.5 | 7.6 |
| 8 in | 30.2 | 17.6 | 13.5 | 11.6 | 9.6 |
| 10 in | 35.1 | 22.1 | 17.0 | 14.3 | 11.7 |
| 12 in | 46.7 | 27.3 | 20.5 | 17.3 | 13.9 |
Cubic feet of grout to fill the VERTICAL cells per 100 sq ft of wall; divide by 27 for cubic yards. Bond beams add grout on top of these. Figures from block-industry estimating data (Fairbanks, Westbrook, Inch Calculator); the 48 in column is interpolated. Solid-fill volume varies about 10 to 25 percent by unit, so confirm with your block supplier. A 4 inch block has no groutable core.
Waste allowance by material
| Material | Waste |
|---|---|
| Block | 5% straight wall, 10% cut-up |
| Mortar | Built into the bag count |
| Grout | 5 to 10% |
| Rebar | 5 to 10% plus code lap splices |
Block waste covers cuts and breakage. The mortar bag rule already carries its own waste, so it is not marked up again. Grout adds a field allowance for spillage and pumping. Rebar laps are set by code and the engineer, never folded into a flat percentage.
Concrete Block Calculator Questions
Start Your Construction Takeoff Today
Upload your first PDF plan set, set the scale, and pull accurate quantities before lunch. $39 a month after the trial, less than every dedicated competitor.