Concrete
Calculator

Concrete Volume Calculator

Enter your dimensions to estimate the volume of concrete required — rectangular, triangular, L-shape and round slabs, round columns, or raft foundations (total trench length × width × depth). Choosing Pool shell switches the estimate to floor slab + wall panels. The calculator adds a 10% allowance for spillage and uneven ground — the industry-standard way to order.

Application Foundations & footings Raft foundation House floor slab Driveway / paving Structural (engineered) Screed / floor topping Difficult access (pump) Pool shell Decorative finish

Shape Rectangular slab / footing Round column Triangular slab L-shape slab Circle / round slab Raft foundation

Number of pours

Length (m)

Width (m)

Thickness (mm)

Diameter (mm)

Height (m)

Base (m)

Height (m)

Thickness (mm)

Overall length (m)

Overall width (m)

Notch length (m)

Notch width (m)

Thickness (mm)

Diameter (m)

Thickness (mm)

Raft mode: enter the total length of all raft trenches — perimeter edge beams plus internal stiffening beams — from your engineer's drawing.

Total trench length (m)

Trench width (mm)

Trench depth (mm)

Pool shell mode: the estimate covers the floor slab + wall panels — the concrete you actually order — not the water volume. Enter the pool's depth and wall thickness below.

Pool depth (m)

Wall thickness (mm)

Calculate Volume

Which Strength Do I Need?

Concrete strength is measured in megapascals (MPa) after 28 days of curing. Typical South African applications:

Application	Typical Strength
House strip footings	15–20 MPa
Residential floor slab	20–25 MPa
Driveway / paving	25–30 MPa
Suspended slabs & columns	30+ MPa (engineer’s spec)
Raft foundations	25–30 MPa (engineer’s spec)
Screeds & toppings	Screed mix

Always confirm the required strength with your engineer or the responsible party before ordering.

How the Calculation Works

Rectangular: length × width × thickness. Triangle: ½ × base × height × thickness. L-shape: (overall length × width − notch length × width) × thickness. Circle: π × radius² × thickness. Round column: π × radius² × height. Raft foundation: total trench length × width × depth. For pool shells we add the walls: perimeter × depth × wall thickness — the concrete you actually order, not the water volume. For more detail read our article on caring for fresh concrete, or see the FAQ.