How thick should a concrete slab be?
Answer
4 inches for patios and walkways, 6 inches for driveways and garages
4 inches: standard for patios, walkways, and shed floors6 inches: required for driveways, garages, and areas with vehicle traffic8 inches: used for heavy equipment, commercial applications, or poor soilAlways pour over 4-6 inches of compacted gravel baseWire mesh or rebar reinforcement is recommended for all slabs 4" and thickerLocal building codes may require specific minimums — check before pouring
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How We Calculated This
Cubic Yards = (Length x Width x Thickness/12) / 27
A 20x20 driveway at 6": (20 x 20 x 6/12) / 27 = 7.41 cubic yards
Related Calculations
How much concrete for a 4×4 slab 4 inches thick?0.20 cubic yardsHow much concrete for a 4×4 slab 5 inches thick?0.25 cubic yardsHow much concrete for a 4×4 slab 6 inches thick?0.30 cubic yardsHow much concrete for a 4×4 slab 8 inches thick?0.40 cubic yardsHow much concrete for a 4×6 slab 4 inches thick?0.30 cubic yards
Calculated using verified formulas. Last updated March 2026.