How to use it
- Enter the Wall Length and Wall Height in meters.
- Enter the Block Length and Block Height in meters. The defaults are 0.4 and 0.2, which is the UAE standard 400 × 200 mm block face.
- Set Wastage (%) for breakage and cutting; the default is 5%.
- Read Wall Area and Blocks Required. For walls with doors or windows, subtract the openings first, as described below.
The formula
Blocks = wall area ÷ block face area, plus wastage. Wall area is length × height, and block face area is block length × block height. A 400 × 200 mm face is 0.08 m², so there are 12.5 blocks per m² of wall before wastage and joints.
Mortar joints and openings
The calculator uses the sizes you enter. Blocks are laid with a mortar joint of about 10 mm, so for a closer count enter the block face including the joint, for example 0.41 × 0.21 m. The result does not subtract doors and windows: remove the opening area by cutting that width or height out of the wall length or height, or run the calculation for each wall section separately.
Block sizes in the UAE
The usual UAE block is 400 mm long by 200 mm high, in thicknesses of 100, 150, 200 and 250 mm for partitions, external walls and boundary walls. Thickness does not change the number of blocks in a wall of a given area, but it does change the weight and the mortar, so choose it from the drawings. Cut blocks around openings and at corners use up part of the wastage allowance.
Worked examples
- A 10 m long, 3 m high partition (30 m²) needs 393.75 blocks of 400 × 200 mm blocks.
- A 40 m villa boundary wall 2.4 m high (96 m²) needs 1,260 blocks.
- A small room wall of 6 m by 3 m with many cut blocks, at 8% wastage, needs 243 blocks.
- A 25 m wall counted with a 10 mm mortar joint (a 0.41 × 0.21 m face) needs 914.634 blocks.
Blocks for a 3 m high wall
Printable chart| Wall length (m) | Wall area (m²) | Blocks (with 5% wastage) |
|---|---|---|
| 1 | 3 m² | 39.375 blocks |
| 2 | 6 m² | 78.75 blocks |
| 3 | 9 m² | 118.125 blocks |
| 5 | 15 m² | 196.875 blocks |
| 6 | 18 m² | 236.25 blocks |
| 8 | 24 m² | 315 blocks |
| 10 | 30 m² | 393.75 blocks |
| 15 | 45 m² | 590.625 blocks |
| 20 | 60 m² | 787.5 blocks |
| 25 | 75 m² | 984.375 blocks |
| 30 | 90 m² | 1,181.25 blocks |
| 40 | 120 m² | 1,575 blocks |
| 50 | 150 m² | 1,968.75 blocks |
| 100 | 300 m² | 3,937.5 blocks |
Shown for 400 × 200 mm blocks, a wall height of 3 m and 5% wastage. Change the fields above for other sizes.
Frequently asked questions
How many blocks are needed per square meter?
With the standard 400 × 200 mm block, 12.5 blocks cover 1 m² of wall before wastage and joints.
What is the standard block size in the UAE?
The standard face is 400 × 200 mm, in thicknesses such as 100, 150, 200 and 250 mm. Enter your supplier’s size in the Block Length and Block Height fields.
Does the calculator subtract doors and windows?
No. Reduce the wall length or height by the opening, or calculate each section of wall separately, then add them up.
How much wastage should I allow for blocks?
5% is the default and a common allowance for breakage and cutting. Increase it for walls with many openings, corners or cut blocks.
Do I need to include the mortar joint?
Only if you want a closer count. Add about 10 mm to the block length and height, for example 0.41 and 0.21 m.
Equipment for this job
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