Solve backwards
How much wall will my concrete blocks build?
- 200 blocksThe example worked below
- Concrete CMU Block Counter & Grout Infill CalculatorEvery figure is its own
You have
How much concrete blocks?
Worked by the Concrete CMU Block Counter & Grout Infill Calculator at the settings below.
The settings it uses
- Wall Height
- 8 ft
- Block Actual Face Length
- 15.6 in
- Block Actual Face Height
- 7.63 in
- Mortar Joint Width
- 0.38 in
- Waste Factor (%)
- 5
- Void Volume per Block
- 2.25 gal
- Grouted Cell Fraction (%)
- 100
- Bond-Beam Courses
- 0
What it will do
169 sq ft of block wall
15.7 m²
One block wall. Enough for 21.2 ft of block wall 8 ft high.
Or several. About 1 block wall of the size the Concrete CMU Block Counter & Grout Infill Calculator opens on: 19.5 ft of block wall 8 ft high.
Check it forwards
- Wall Length
- 21.2 ft
- It asks for
- 200 blocks
- You have
- 200 blocks
The Concrete CMU Block Counter & Grout Infill Calculator asks for 200 blocks at that size, and 201 blocks one step larger.
If you had more, or less
Around your amount
Each worked by the Concrete CMU Block Counter & Grout Infill Calculator at the same settings.
Half
100 blocks
84.7 sq ft
10.6 ft of block wall 8 ft high
Yours
200 blocks
169 sq ft
21.2 ft of block wall 8 ft high
Half as much again
300 blocks
254 sq ft
31.7 ft of block wall 8 ft high
Double
400 blocks
339 sq ft
42.3 ft of block wall 8 ft high
Common amounts
What each amount of concrete blocks covers
The sizes it is usually sold in, each worked by the Concrete CMU Block Counter & Grout Infill Calculator at the settings above.
| You have | It covers | As one block wall | Average block walls |
|---|---|---|---|
| 50 blocks | 42.3 sq ft(3.93 m²) | 5.3 ft of block wall 8 ft high | under 1 |
| 100 blocks | 84.7 sq ft(7.86 m²) | 10.6 ft of block wall 8 ft high | under 1 |
| 200 blocks | 169 sq ft(15.7 m²) | 21.2 ft of block wall 8 ft high | 1 |
| 500 blocks | 423 sq ft(39.3 m²) | 52.9 ft of block wall 8 ft high | 2 |
One block to about eight-ninths of a square foot
A nominal 8 by 8 by 16 inch block is 7⅝ by 15⅝ inches actual, and with a ⅜ inch joint it lays 1.125 to the square foot. The 440 by 215 mm block common in metric markets lays about 10 to the square metre with a 10 mm joint. The count is gross — openings are not taken off — so a wall with a doorway stretches further.
Every cut is a whole block
Five per cent covers cuts and breakage on a straightforward rectangular wall on a flat site, and read backwards it comes off the pallet. Many openings, short returns or a rake want more — every cut is a whole block off the pallet, and the offcut is rarely the size the next cut needs.
Every block here is a plain stretcher
Nothing is set aside for the half, corner, bond-beam, lintel or sash units a real course layout needs, and the grout for filled cells is a separate figure the block calculator also works out. Which cells are grouted, and whether the wall carries its load, come from the structural drawings and the masonry code.
How the answer is worked
Nothing here is a second formula. The Concrete CMU Block Counter & Grout Infill Calculator runs forwards — a size in, a quantity out — and this page grows its own starting block wall in proportion until the quantity it asks for is what you have. Where it rounds up to whole containers, the answer is the largest size before the next one would be needed.
Where the calculator adds an allowance for cuts or breakage when you order, the same allowance comes off here, because it is the same calculator: a stack you already own finishes less than its face value. Where it adds none, neither does this page — the settings beside the answer say which.
Concrete CMU Block Counter & Grout Infill Calculator
runs it forwardsEstimate CMU block count and grout volume for reinforced masonry, calculated dynamically from your actual block dimensions and mortar joint width.
Work out what to buy insteadSolve backwards
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Solve backwards
Start from what is already in the yard
Paint, sheets, rolls, bags and pieces, each read the other way by the calculator that orders it.
The calculator's own figures
Nothing is estimated twice: the page runs the same calculator you would order with.
The largest size that fits
Where a calculator rounds up to whole containers, the answer stops before the next one.
Both unit systems
Gallons and litres, square feet and square metres, side by side.
Frequently asked questions
- How much block wall does 200 blocks of concrete blocks cover?
- At the Concrete CMU Block Counter & Grout Infill Calculator's own settings, 169 sq ft (15.7 m²) — 21.2 ft of block wall 8 ft high. That is about 1 block wall of the size the calculator opens on: 19.5 ft of block wall 8 ft high. Every figure follows the settings, which you can change in the calculator.
- How many concrete blocks are in a square foot of wall?
- A standard 8 by 8 by 16 inch block with a ⅜ inch joint lays 1.125 blocks per square foot — 112.5 per 100 square feet. A 440 by 215 mm metric block lays about 10 per square metre with a 10 mm joint. Add about five per cent for cuts and breakage.
- How long a wall will 200 blocks build?
- About 169 square feet (15.7 m²) of 8 by 16 inch block once five per cent comes off for cuts — a wall about 21 feet long at 8 feet high. With 440 by 215 mm blocks, about 19 m², or roughly 8 metres at 2.4 m high.
- Do I subtract windows and doors when counting blocks?
- The block calculator does not — its count is the gross wall — so subtract large openings yourself. Remember that an opening takes a lintel or bond-beam course and jamb units, so the blocks it saves are not all plain stretchers you can use elsewhere.