Concrete Volume Calculator (cubic meters)
Multiplies slab width, length and thickness in meters and returns the cubic meters of ready-mix needed, rounded to 3 decimals; no waste margin added.
Volume (m³)
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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.
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The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.