How this concrete calculator works
Mix-first workflow: begin from a known pour volume, then explore how ratio shifts affect cement bags versus sand and stone — ideal for batch planning at the plant or jobsite.
How to calculate concrete volume
Multiply footprint area by thickness (height of the pour). For a rectangular slab, V = L × W × T. Circles use V = π × r² × T. Triangles use footprint area ½ × base × height times thickness.
What is a mix ratio?
Ratios like 1:2:4 describe relative volumes of cement : fine aggregate (sand) : coarse aggregate before water is added. Richer mixes (more cement) generally gain strength but cost more.
Material estimation notes
We expand wet volume to dry materials using a 1.54 bulk factor and your wastage percentage. Densities are typical defaults (cement ~1440 kg/m³). Always validate against local batch plant guidance.
Construction tips
- Order 5–10% extra for uneven subgrades and spillage — adjust the wastage slider accordingly.
- Coordinate pump or chute access before locking truck counts.
- Keep reinforcement clear cover consistent; spacing assumptions here are informational.