Construction & estimating · Concrete & reinforcement

Concrete materials estimate calculator

Cement bags, sand, aggregate and water for site-mixed concrete by ratio, with wastage.

Standard: Nominal mix, dry-volume method · AS 1379 for premix

Inputs in the worked example

The live calculator starts with these values; change any of them and every result, check and diagram updates instantly.

Diagram for the worked example

Dry volume = wet × 1.54 (voids and bulking)
Each part = dry × ratio / Σratio; cement 1440 kg/m³
Sand ≈ 1.6 t/m³, aggregate ≈ 1.5 t/m³ (loose)
Structural concrete in Australia is normally premixed to AS 1379 and specified by grade (N20, N25, N32…); nominal mixes suit minor works.

Bar schedule & rebar weight — Reinforcement mass by bar mark, totals by diameter and tonnage to order.
Formwork contact area — Formwork area for slabs, beams, columns and footing edges, ply sheets allowing for re-use, and cost.
Concrete volumes & cost — Volumes for footings, slabs, beams and columns, order quantity rounded to 0.2 m³, trucks and cost.
Reinforcement quantities & cost — Steel tonnage from a kg/m³ ratio or a bar list, with laps and waste, supply and fix cost.
Earthworks cut & fill — Volumes from cross-section areas, loose and compacted volumes, truck loads and a mass-haul diagram.
Excavation, cart-away & disposal — Excavated bank volume with batters, bulking, backfill retained, truck loads, tonnes to tip and cost.

For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.