How Thick Should a Concrete Slab Be?
Thickness is the fastest way to blow a concrete estimate — an extra inch across a big slab is a lot of yards. Match the thickness to the load.
Thickness by use
Four inches handles patios, shed floors and walkways. Driveways for cars go 5–6 inches; anything carrying RVs, trucks or equipment wants 6 inches or more, often with rebar. Local code and soil can raise these — check before you pour.
Why thickness drives the yardage
Volume is length × width × thickness, so an inch of extra depth on a 400 sq ft slab adds about 1.2 cubic yards — real money. The slab calculator shows exactly how thickness changes the order and the cost.
FAQ
How thick should a concrete slab be?
4 inches for patios, sheds and walkways; 5–6 inches for driveways; 6 inches or more for heavy vehicles or garages, subject to local code.
Does slab thickness change how much concrete I need?
Yes, directly — volume scales with thickness. An extra inch over a large slab adds meaningful cubic yards.