Volume de Concreto (m³)

Concrete volume in cubic meters

The formula is V = length × width × thickness, all in meters. Example: a slab of 50 m² × 0.12 m thick = 6 m³. For residential structural concrete, the usual spec is fck 25 MPa. Each 1 m³ of fck 25 takes about 350 kg cement, 850 kg sand, 1050 kg gravel and 175 L water (w/c ≈ 0.5), which is roughly 7 bags of 50 kg cement. Before pouring, the slump test (cone) checks workability. Mix it too dry and it won't fill properly; too wet and you lose strength.

Applications and standards

Handy for sizing the volume of a foundation, subfloor, slab, beam or paving when you're putting together a budget or ordering material. Brazilian standards: NBR 6118 (reinforced concrete structures) and NBR 12655 (concrete production and acceptance). On structural elements, stick to the engineer's project. The calculator only gives you the volume.

FAQ

Should I add a safety margin? Yes. Tack on 5–10% for losses such as spillage, an irregular surface, or residue left in the pump.

On-site or ready-mix concrete? Past 5 m³, ready-mix (usinated) tends to be cheaper and more consistent. Below that, mixing on site with a mixer is common.

What thickness for a residential slab? Figure 10–12 cm for a one-way prestressed slab, 8–10 cm for subfloor, and 15+ cm for a solid slab. Always confirm against the structural project.