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Concrete Calculator

Estimate concrete yards, bags, and compacted base for patios, sidewalks, small pads, slabs, and residential driveways.

Interactive slab planner

Concrete slab preview

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Enter an area to preview your slab
Sample patio preview
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Sample patio
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Your estimate

-- cu yd ready-mix

Enter slab area to estimate concrete, base, and cuts.

Order list

  • MIXReady-mix concreteSelected path: order by cubic yard--
  • ALTBagged mix alternativeComparison only; do not order both paths--
  • BASECompacted gravelSuppliers may quote by cubic yard or ton--

Prep list

  • CUTSSaw cuts10 ft spacing, 1 in deep--
  • DIGDig depth if flush to grade4 in slab + 4 in base - 0 in above grade--
  • BASEBase prepCompact aggregate and confirm drainage before the pour--
  • CHECKPlanning noteMaterial planner only; not structural, permit, or code guidanceReview
How the estimate is calculated

Concrete volume is area multiplied by slab depth. The calculator adds your buffer before converting to cubic yards and bags.

Concrete cubic feet = area × (slab depth ÷ 12)

Total concrete = concrete cubic feet + buffer

Cubic yards = total concrete cubic feet ÷ 27

Bags = total concrete cubic feet ÷ bag yield, rounded up

Base tons = base cubic yards × 1.5

Dig depth = slab depth + base depth - finished height above grade

Planning checks

Ready-mixCall with cubic yards and ask about minimum loads, truck access, and chute reach.
Bagged mixUse bags for small pads and repairs. Larger slabs become a lot of lifting and mixing.
PrepCompact the base, plan drainage, and keep control-joint panels close to square.
DrivewaysHeavy loads, weak soils, reinforcement, or permits need local guidance.

Concrete calculator FAQ

  • How thick should a patio or sidewalk slab be?

    Four inches is a common planning depth for patios, walkways, and small pads on a properly prepared base. Local conditions, loads, and codes can change that.

  • How thick should a driveway slab be?

    Residential driveways often plan around 5 to 6 inches depending on vehicle loads and base prep. Heavy vehicles, poor soil, or local requirements may need a stronger design.

  • Is this calculator for foundations or building slabs?

    No. This is a material planner for residential flatwork such as patios, sidewalks, small pads, slabs, and driveways. Structural work needs local code and professional guidance.