How many concrete blocks do I need per square metre in South Africa?

Standard South African concrete blocks (Maxi, Midi, and Mini) all have the same face area of 390×190mm, giving approximately 12.5 blocks per square metre of wall face. Add 5–10% for waste and cuts.

What is the difference between Maxi, Midi, and Mini blocks?

All three are 390mm long × 190mm high. They differ in thickness: Maxi = 190mm (exterior walls, structural), Midi = 140mm (interior load-bearing), Mini = 90mm (partition walls, fencing). Maxi is the most common for SA house construction.

How many bags of cement do I need for 100 concrete blocks?

Approximately 1.2 bags of cement (50 kg) and 3 bags of sand per 100 blocks, based on a 1:3 cement:sand mortar mix at 0.012 m³ mortar per block. Always buy 10% extra for waste.

What does a concrete block cost in South Africa in 2026?

As of 2026: Maxi blocks R12–R15 each, Midi R10–R12, Mini R8–R10. Prices vary by region and supplier. Buying in bulk (1,000+) typically saves 10–15%. Always get quotes from local suppliers in your area.

What is a DPC layer and do I need one?

DPC (Damp Proof Course) is a horizontal membrane installed at foundation level to prevent rising damp. SANS 10400 requires DPC in all South African buildings. It is typically a layer of bitumen-impregnated sheet or two courses of plastered brickwork.

Concrete Block Calculator South Africa

Calculate concrete blocks, mortar (cement + sand), and estimated costs for walls in South Africa. Supports Maxi, Midi, and Mini blocks with door/window opening deductions and SVG wall visualisation.

⚡ Quick Calculator Get a fast estimate

Wall Length

Wall Height

Block Size

Blocks Required

315

Wall Area

24.0 m²

Cement Bags (50 kg)

Sand Bags

Estimated Block Cost

R 4 253

Estimated Mortar Cost

R 9 870

Total Estimated Cost

R 14 123

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How to Use the Block Calculator

Enter your wall length and height in metres, then select your block size. The calculator gives you blocks required (with 5% waste), cement bags, sand bags, and an estimated cost range based on 2026 South African prices.

The Extended Calculator handles multiple walls, door and window deductions, and shows an SVG wall pattern. The Professional Calculator adds lintels above openings, DPC layers, horizontal rebar reinforcement, and full project export.

Need more detail?

📊 Extended Calculator More options, charts, and scenario comparison

Wall Name

Block Size

Length (m)

Height (m)

Waste Factor

Openings (Deductions)

Total Blocks Required (all walls)

315

Net Wall Area

24.0 m²

Cement Bags

Sand Bags

Block Cost (est.)

R 4 253

Mortar Cost (est.)

R 9 870

Total Estimated Cost

R 14 123

South African Block Sizes Reference

Block Type	Dimensions (L×H×T)	Blocks/m²	Use Case	Price Range
Maxi	390×190×190mm	12.5	External/structural walls	R12–R15
Midi	390×190×140mm	12.5	Internal load-bearing	R10–R12
Mini	390×190×90mm	12.5	Partition walls, garden walls	R8–R10

Prices as of 2026. Vary by region and supplier. Always confirm with local builders merchants.

Block & Mortar Calculation Formula

Wall Area (m²) = Length × Height − Opening Areas Blocks = Wall Area × 12.5 × (1 + Waste %) Mortar Volume (m³) = Blocks × 0.012 Cement Bags = Mortar Volume × 8 (50 kg bags, 1:3 mix) Sand Bags = Mortar Volume × 20

Material Quantities for Common Wall Sizes

Wall Size	Maxi Blocks	Cement Bags	Sand Bags	Est. Cost (Maxi)
5m × 2.4m (12 m²)	158	15	38	≈ R3,500
10m × 2.4m (24 m²)	315	30	76	≈ R6,900
20m × 2.4m (48 m²)	630	61	151	≈ R13,800
30m × 3m (90 m²)	1,182	114	283	≈ R25,900

Includes 5% waste. Cost at mid-range Maxi price (R13.50). Mortar costs included.

SANS 10400 Building Regulations Notes

Foundation depth: Minimum 300mm below ground level in most SA soil types (deeper for clay/expansive soils).
DPC: Required at least 150mm above finished ground level under SANS 10400-B.
Lintels: Required above all door and window openings. Width = opening + 300mm bearing each side.
Wall ties: Required for cavity walls and where walls abut at corners without bonding.
Always consult an engineer for walls over 3m or retaining walls.

Need full precision?

🔬 Professional Calculator Complete parameters, sensitivity analysis, and detailed breakdown

Name

Wall Type

Length (m)

Height (m)

Block Size

Waste Factor

No. of Openings

Opening Width (m)

Include DPC LayerHorizontal Rebar (Y10)

Full Project Material List

R 13 645

Total Blocks

291

Cement Bags

Sand Bags

Block Cost

R 3 929

Mortar Cost

R 9 030

Lintels Cost

R 336

DPC Cost

R 350

Delivery Trucks (est.)

Frequently Asked Questions

Standard SA concrete blocks (Maxi, Midi, Mini) all measure 390×190mm on the face, giving approximately 12.5 blocks per m². Add 5–10% for waste and cuts. So a 10m × 2.4m wall (24 m²) needs about 315 blocks including waste.

All three are 390mm × 190mm (face size). Thickness differs: Maxi = 190mm (used for external/structural walls), Midi = 140mm (internal load-bearing), Mini = 90mm (partition walls, boundary fencing). Maxi is the SA standard for house construction.

Approximately 1.2 bags cement (50 kg) and 3 bags sand for 100 blocks, using a 1:3 mix. This is based on 0.012 m³ mortar per block × 8 cement bags/m³. Always buy 10% extra to account for waste.

2026 prices: Maxi R12–R15, Midi R10–R12, Mini R8–R10 per block. Buying in bulk (1,000+) typically saves 10–15%. Prices vary by region — Cape Town and Johannesburg may differ by 15–20% from smaller centres.

DPC (Damp Proof Course) is a horizontal moisture barrier installed at foundation level to prevent rising damp. SANS 10400-B requires DPC in all SA buildings at a minimum of 150mm above finished ground level. It typically costs R25–R40 per linear metre.

Concrete Block Calculator South Africa

How to Use the Block Calculator

South African Block Sizes Reference

Block & Mortar Calculation Formula

Material Quantities for Common Wall Sizes

SANS 10400 Building Regulations Notes

Frequently Asked Questions

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