Concrete Slab Calculator
Find cubic yards of concrete needed for any slab project. Includes reinforcement options, strength recommendations, and cost breakdown.
Length of concrete slab
Width of concrete slab
Depth/thickness of concrete
Determines recommended depth and reinforcement
Reinforcement prevents cracking
Compressive strength rating
Always add 10% for spills and over-excavation
How do I calculate concrete needed for a slab?
Multiply length × width × depth in feet, then divide by 27 to get cubic yards. Always add 10% wastage for spills, over-excavation, and settling. For a 10×10×4" slab: 10×10×0.333 / 27 = 1.23 cubic yards, round to 1.35 with waste.
What strength concrete do I need for different projects?
3000 PSI is standard for most residential slabs (patios, garages). Use 4000 PSI for driveways and freeze-thaw climates. 5000 PSI for commercial or heavy vehicle loads. Footings can use 2500 PSI since they bear loads from below ground.
Do I need rebar in concrete slabs?
Yes, always reinforce concrete. Wire mesh (6×6-W2×W2) is minimum for slabs under 5" thick. Use #4 rebar in a grid (16-24" spacing) for driveways and heavy loads. Rebar doesn't prevent cracking but holds cracks together and adds tensile strength.
How much does concrete delivery cost?
Most concrete companies charge a delivery fee of $150-200 for small loads (under 3 yards) and include it in the yard price for larger orders. Minimum load is typically 1 yard. Full truck holds 8-10 yards. Plan for 5-10 minute per yard pour time plus setup/cleanup.