Concrete Slab Calculator
How to Use This Calculator
Select your slab shape (rectangle, circle, or triangle), enter the dimensions in feet and inches, set the thickness, and adjust the waste percentage. The calculator instantly shows the concrete volume in cubic yards, total area, and weight.
Toggle optional sections for cost estimates and labor pricing to get a complete project budget.
Formulas
Rectangle: Volume = Length × Width × Thickness
Circle: Volume = π × (Diameter/2)² × Thickness
Triangle: Volume = 0.5 × Base × Height × Thickness
Conversion: 1 cubic yard = 27 cubic feet
Weight: ~4,050 lbs per cubic yard of concrete
Frequently Asked Questions
How thick should a concrete slab be?
4 inches for patios and walkways, 6 inches for driveways, 8+ inches for garages and heavy loads.
How much waste should I add?
5–10% for simple rectangular slabs, 10–15% for irregular shapes or if forms aren't perfect.
Should I use ready-mix truck or bags?
For anything over 1 cubic yard (~27 ft³), a ready-mix truck is cheaper and easier. Bags are for small repairs and projects under 0.5 yd³.
