Concrete Slab Calculator

Estimate concrete slab area, cubic yards, and number of bags required. For basic surface measurement, use our Floor Area Calculator.

You May Also Like:

Floor Area Roof Area Tile Calculator Wall Area
Concrete Needed: —
Formula:
Area = Length × Width
Volume (ft³) = Area × Thickness (ft)
Cubic Yards = Volume ÷ 27
Example:
20 × 15 = 300 ft²
4" thick → 1 ft³ per 3 ft²
300 × (4/12) = 100 ft³
100 ÷ 27 ≈ 3.7 cubic yards

Frequently Asked Questions

How thick should a concrete slab be?

Most residential slabs are 4–6 inches thick depending on load requirements.

Why calculate cubic yards?

Concrete is typically sold by the cubic yard for truck delivery.

Should I order extra concrete?

Yes. Add 5–10% extra for safety and spillage.