Block Brick Calculator South Africa: How Many Bricks

This calculator works out how many bricks or blocks you need for a wall in South Africa. You enter the wall’s length and height, the brick size, and the mortar joint thickness, and it returns the number of bricks required, including a wastage allowance. It also shows the wall area in square metres, which helps when ordering cement and sand.

Formula

The number of bricks is found by dividing the wall area by the area of one brick plus its mortar joint. In symbols:

Bricks = (Wall length × Wall height) / ((Brick length + Joint) × (Brick height + Joint))

Where:

• Wall length (m) – horizontal distance of the wall.
• Wall height (m) – vertical distance from foundation to top.
• Brick length (mm) – the longest face dimension.
• Brick height (mm) – the vertical dimension when laid.
• Mortar joint (mm) – typical thickness of the bed and perpend joints.
• Wastage (%) – extra bricks for breakage and cutting.

All dimensions must be in the same units. The calculator converts millimetres to metres automatically.

Worked Example

Using the default values: wall length 10 m, height 2.4 m, brick length 222 mm, height 73 mm, joint 10 mm, wastage 10%.

1. Convert brick dimensions to metres: length = 0.222 m, height = 0.073 m.
2. Add joint: effective length = 0.222 + 0.010 = 0.232 m; effective height = 0.073 + 0.010 = 0.083 m.
3. Wall area = 10 × 2.4 = 24 m².
4. Area per brick with joint = 0.232 × 0.083 = 0.019256 m².
5. Number without wastage = 24 / 0.019256 ≈ 1246.4 bricks.
6. Add 10% wastage: 1246.4 × 1.10 ≈ 1371 bricks.

The calculator rounds up to 1371 bricks. Always round up, never down, because you will need to cut bricks at corners and openings.

Standard Brick Sizes in South Africa

South Africa uses the metric system, and the most common brick sizes are:

• Imperial brick (222 × 106 × 73 mm) – the default in this calculator, widely used for houses.
• Maxi brick (290 × 90 × 90 mm) – larger, laid with thinner joints, often used for faster construction.
• Masonry blocks (390 × 190 × 140 mm or 390 × 190 × 190 mm) – hollow or solid concrete blocks for foundations and large walls.

If you use a different size, simply change the length, depth, and height fields. The depth (width of the wall) does not affect the number of bricks on the face, but it matters for material volume and foundation design.

How to Choose the Right Brick

Your choice depends on the wall’s purpose and the load it carries.

• Face bricks – used for exposed walls, come in various textures and colours, and are more expensive.
• Common bricks – used where the wall will be plastered or painted; they are cheaper but less uniform.
• Concrete blocks – for foundations, retaining walls, or industrial buildings; they are larger and need fewer units.
• Maxi bricks – a good compromise between speed and appearance, often used for single-storey houses.

Check with your local supplier for the exact dimensions of the bricks you plan to buy, as slight variations exist between manufacturers. The calculator’s default is typical for a standard imperial brick, but confirm before ordering.

Common Mistakes and How to Avoid Them

• Forgetting the mortar joint – a 10 mm joint is standard, but some brick types use 12 mm. Always measure the joint you intend to use.
• Mixing units – if you enter the wall in metres and the brick in millimetres, the calculator handles the conversion, but if you calculate manually, convert everything to the same unit first.
• Ignoring openings – the calculator gives the full wall area. Subtract the area of windows and doors before ordering, or add a higher wastage to cover the extra cutting.
• Not rounding up – always round up to the nearest whole brick. Partial bricks are not sold.
• Underestimating wastage – 10% is a safe minimum for a simple wall. For walls with many corners, arches, or complex patterns, use 15%.

Limitations of the Formula

This calculation assumes a single-skin wall (one brick thick) with a flat, rectangular face. It does not account for:

• Brick bonds – English, Flemish, or stretcher bonds may require different numbers of cut bricks, but the total quantity remains similar.
• Reinforcement or cavity walls – these need more materials and different calculations.
• Mortar volume – the calculator gives brick count only, not the amount of cement and sand. For mortar, you need to know the volume of joints, which depends on the brick depth.
• Foundation and lintels – these are separate material quantities.

For a double-skin wall (two brick layers), simply multiply the result by two. For a cavity wall with a gap, you still need two layers, so the same multiplication applies.

Frequently Asked Questions

How many bricks are in a square metre in South Africa?

With a standard imperial brick (222 × 73 mm) and a 10 mm joint, you need about 52 bricks per square metre (including wastage). Without wastage, it is about 52.0 bricks per m². For maxi bricks (290 × 90 mm), you need around 33 bricks per m².

How do I calculate the number of bricks for a wall with a window?

Calculate the full wall area as shown, then subtract the window area (width × height) from the wall area before multiplying by the bricks per square metre. Add 10% wastage for cutting around the frame. For example, a 1 m × 1.2 m window reduces the area by 1.2 m², which is about 62 bricks.

What is the difference between a brick and a block?

In South Africa, a brick is a clay or concrete unit that can be laid with one hand, typically smaller than 300 mm in length. A block is a larger concrete unit, usually 390 mm long, used for foundations and large walls. Blocks cover more area per unit, so you need fewer of them, but they are heavier and may require two hands to lay.

How much mortar do I need for 1000 bricks?

For a standard imperial brick with a 10 mm joint, you need roughly 0.3 m³ of mortar per 1000 bricks. This is a rule of thumb; the exact volume depends on the joint thickness and the brick depth. A typical mix is 1 part cement to 4 parts sand by volume, but always follow your engineer’s specification.

Can I use this calculator for concrete blocks?

Yes. Enter the block’s length and height in millimetres, and set the joint to 10 mm (or 12 mm if that is your practice). The calculator will give the number of blocks needed. For a 390 × 190 mm block with a 10 mm joint, you need about 12.5 blocks per square metre.

Why do I need to add wastage?

Bricks break during transport, cutting, and handling. Also, you will need half-bricks at corners and ends. A 10% allowance covers these losses without leaving you short. If you are building a wall with many openings or a decorative pattern, increase the wastage to 15%.

Final Tips for Ordering

Always order a few extra bricks beyond the calculated number, because manufacturers may discontinue a colour or texture. Keep the extra bricks in a dry place for future repairs. When ordering, also plan for the mortar: a typical 50 kg bag of cement mixed with sand covers about 100 bricks, but this varies with the mix ratio and joint thickness. Confirm your supplier’s pallet quantities, as bricks are often sold per pallet, and the number per pallet varies by brick size.

Related

• Drywall Calculator Metric: Sheets & Waste
• Drywall Calculator by Square Footage
• Drywall Calculator by Wall: Sheets & Cost

in l | Wall length | m | 10 | 0
in h | Wall height | m | 2.4 | 0
in bl | Brick length | mm | 222 | 0
in bd | Brick depth | mm | 106 | 0
in bh | Brick height | mm | 73 | 0
in j | Mortar joint | mm | 10 | 0
in w | Wastage | % | 10 | 0
out bricks | Bricks needed | bricks | ceil((l / ((bl + j) / 1000)) * (h / ((bh + j) / 1000)) * (1 + w / 100)) | 0
out area | Wall area | m² | l * h | 2