Concrete & gravel cubic-yard conversions
A cubic yard is 27 cubic feet, so concrete or gravel volume = area (sq ft) × thickness (ft) ÷ 27, and thickness in inches is divided by 12 first. That is a fixed convention, not a price. The table shows cubic yards for common slab sizes; add your own $/cu yd in the slab, footing and French drain tools.
| Area | Thickness | Concrete (cu yd) |
|---|---|---|
| 100 sq ft | 4 in | 1.23 cu yd |
| 200 sq ft | 4 in | 2.47 cu yd |
| 400 sq ft | 4 in | 4.94 cu yd |
| 400 sq ft | 6 in | 7.41 cu yd |
| 600 sq ft | 4 in | 7.41 cu yd |
27 cubic feet = 1 cubic yard; cu yd = area × (thickness in ÷ 12) ÷ 27. Order a little extra for spillage and uneven subgrade.