Concrete cubic yards for a slab.
Volume = Length × Width × Thickness. Converted to cubic yards (US standard for concrete orders).
1 cubic yard = 27 cubic feet. Order 5–10% extra for spillage and uneven ground.
Ready-mix suppliers price and deliver by the cubic yard, not the cubic foot, which is why converting the raw volume calculation into yards matters for actually placing an order, not just for the math itself.
10 ft × 10 ft × 4 in thick = 100 × 0.333 = 33.3 cu ft = 1.23 cu yd.
Small pours (<1 cu yd) often use bagged mix. Larger pours: ready-mix trucks minimum ~1 cu yd, often 3+ minimum.
4 in for cars, 6 in for trucks or heavy vehicles. Check local codes.
Uneven subgrade, minor spillage, and formwork imperfections routinely eat into the exact calculated volume — a 5-10% buffer avoids running short mid-pour, which is far more costly than having a small amount left over.