Civil Engineering · Concrete
Concrete Volume & Weight
Volume and weight of concrete for slabs, columns, and footings — for material quantity and procurement estimates.
Standard method — stated scope limits apply
Element
Choose a shape and enter dimensions.
About This Calculation
Concrete volume and weight calculations are the first step in almost every concrete pour — slab, footing, or column — and the material order, formwork design, and crane/pump sizing all depend on getting the volume right. The geometry itself is exact (length × width × thickness for a slab, or the circular equivalent for a round column); the only real variable is the unit weight, which depends on the actual mix and aggregate used rather than being a single universal constant.
Frequently Asked Questions
What unit weight should I use for normal concrete?
2400 kg/m³ is the commonly used default for normal-weight reinforced concrete, but the real figure depends on the aggregate type and mix — lightweight concrete can be well under 2000 kg/m³, and dense/heavyweight mixes can exceed 2500 kg/m³.
Should I add extra volume for wastage?
Yes, in practice — this calculator gives the exact geometric volume; site practice commonly adds 3–5% for spillage, formwork imperfection, and over-excavation, especially for footings poured against undisturbed soil.
Does this include the volume taken up by reinforcement steel?
No — rebar volume is normally small enough relative to the concrete volume to be ignored in a quantity estimate, and is conventionally not subtracted. For a very heavily reinforced section this becomes a more significant simplification worth checking.
How is a circular column’s volume calculated differently from a rectangular one?
A circular column uses π/4 × diameter² × height for its cross-sectional area instead of width × thickness — the same basic volume = area × height relationship, just with a circular cross-section.