Concrete Calculator
Volume, cement, sand, stone, and cost for a concrete pour.
Work out how much concrete a slab, footing, or column needs — the volume in m³, the cement/sand/stone breakdown, and an estimated cost using SA ready-mix benchmark rates.
- Concrete volume2.20 m³2.00 m³ + 10% waste
- Cement (50 kg bags)~7 bags/m³16 bags
- Sand & stone1 : 2 : 3 mix approx1.1 m³ sand · 1.7 m³ stone
- Estimated ready-mix costR 2 425/m³ (25 MPa, incl. placing)R 5 335
Assumes a 1:2:3 nominal mix (~7 × 50 kg cement bags per m³). Ready-mix rate from NNAQS benchmark data. Confirm mix design with your engineer for structural work.
Questions
- How many bags of cement in 1 m³ of concrete?
- About 7 × 50 kg bags for a general 25–30 MPa mix at a 1:2:3 ratio. Higher-strength mixes use more cement; always follow the engineer's mix design for structural elements.
- Should I order ready-mix or mix on site?
- For anything above ~2 m³, ready-mix is usually cheaper and more consistent once you account for labour, wastage, and cube-testing. Below that, site mixing can make sense.
- How much waste should I allow?
- 10% is a safe default for slabs and footings to cover over-excavation, spillage, and uneven substrate. This calculator already adds it.
Compiled by Setout. Figures are planning-stage estimates, not quotes.