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Concrete Cubic Metre Calculator

Determine the exact volume of ready-mix concrete required for house foundations, driveway slabs, and structural footings. Includes automatic truckload scheduling (6 m³ trucks) and 10% safety overage.

Concrete Slab & Footing Volume (m³)

Real-time volumetric & tonnage modeling (SABS & ISO Metric SI compliant)

Standard residential concrete slabs are typically 100 mm to 150 mm thick.

2.40 t/m³ (2,400 kg/m³)
+10%
0% (Exact void)+5%+10% (Recommended)+15%+25% (Excavation)
Gross Volume (Order Quantity)Live Calc
8.250m³

Includes +10% waste over net physical volume.

Net Physical Void7.500m³
Total Liquid Volume8,250L
Total Weight (t)19.80tonnes
Ready-Mix Deliveries~1.4trucks (6m³)
Imperial EquivalentsUS Customary
Cubic Yards: 10.79 yd³
Cubic Feet: 291.35 ft³
Mathematical Derivation & Proof
SI Metric Model

Formula: V_net = Length × Width × Depth

V_net = 10.000 m × 5.000 m × 0.150 m = 7.500 m³

1. Normalizing inputs to metres: L = 10.000 m, W = 5.000 m, D = 0.150 m
2. Net volume: 10.000 × 5.000 × 0.150 = 7.500 m³
3. Factoring +10% waste allowance: 7.500 × 1.10 = 8.250 m³
4. Total mass @ 2.40 t/m³ (Concrete): 8.250 × 2.40 = 19.80 tonnes
5. Standard 6 m³ truckloads: 8.250 / 6 = ~1.4 loads (order 2 trucks)

Standard Slab Thickness Specifications (South Africa)

75 mm – 100 mm (0.075 – 0.10 m)Pedestrian Pathways & Shed Bases

Light duty walkways, patio pavers base, and garden tool shed foundations without vehicle loads.

125 mm – 150 mm (0.125 – 0.15 m)Residential Driveways & Garages

Passenger vehicles, light bakkies, and garage floors reinforced with Ref 193 steel wire mesh.

200 mm+ (0.20 m+)Commercial Delivery & Heavy Trucking

Heavy goods vehicle hardstands, workshop floors, and high-load industrial raft foundations.

How Cubic Metre Calculation Works

The engineering mathematics behind volumetric measurement, compaction allowances, and ready-mix batching.

01

Normalize to Metres (m)

Slab thickness and trench depths are commonly specified in millimetres (e.g., 150 mm) or centimetres (15 cm). Convert all dimensions to metres before multiplying:

Depth (m) = mm ÷ 1,000
150 mm ÷ 1,000 = 0.150 m
02

Solve Net Volume (m³)

Multiply length by width and depth to determine the net physical void space. For cylinders (round tanks, circular slabs), multiply base area ($\pi r^2$) by height:

V_net = L × W × D
10.0 m × 5.0 m × 0.15 m = 7.50 m³
03

Apply Compaction & Waste

Excavated subgrades settle, formwork flexes under hydraulic pressure, and pumps retain residual mix. Always factor 5% to 15% extra for realistic batching:

V_order = V_net × (1 + Waste %)
7.50 m³ × 1.10 (+10%) = 8.25 m³

Concrete Batching & Slab FAQs

Common questions regarding metric cubic metre calculations, bulk densities, and material batching.

How do you calculate concrete in cubic metres for a slab?
Measure the length and width of the formwork in metres, and the slab thickness in millimetres. Divide the millimetres by 1,000 to convert to metres, then multiply: Length × Width × Depth. Add 10% for waste and ground irregularities.
How many bags of cement make 1 cubic metre of concrete?
For standard 25 MPa concrete mixed on-site, one cubic metre requires approximately 6 to 7 x 50 kg bags of cement, 0.65 m³ of building sand, and 0.85 m³ of crushed stone (19 mm), mixed with clean water.
What is the capacity of a standard ready-mix concrete truck?
Standard ready-mix concrete delivery trucks in South Africa transport 6.0 m³ of wet concrete. Some larger commercial barrel trucks carry 8.0 m³, while mini-mix trucks transport 3.0 m³ to 4.0 m³ for difficult-access residential properties.
Why must I order extra concrete for waste?
Excavated soil is never laser-flat, formwork boards bulge outward under wet hydrostatic pressure, and concrete pump pipelines retain residue. Ordering 10% extra prevents cold joints caused by running short.