Concrete slab cost is driven mostly by size, thickness, and use, but the gravel base, reinforcement, and finish add real cost that a bare per-square-foot number misses. The inputs below account for all of it so the number you see reflects a real slab, not a textbook average.
Last reviewed September 2026
| Line item | Low | Mid | High |
|---|
| Thickness | Low | Mid | High |
|---|
Enter your email and we’ll save it. We’re building the newsletter now. No spam, cancel any time.
This calculator starts with a per-square-foot installed cost that scales directly with your chosen thickness, fit to HomeGuide's own published 2026 thickness table, then adds reinforcement and finish as separate per-square-foot line items, and applies a labor cost multiplier for your region. Contractor-Installed pricing uses HomeGuide's own published materials-to-labor split (55 percent materials, 45 percent labor). Switching to DIY replaces that split with a bottom-up materials estimate: real cubic yards of concrete (by ready-mix truck or by 80 lb bag, your choice), a compacted gravel base, and the reinforcement you would actually buy (wire mesh sheets or rebar by the linear foot), so the DIY number reflects an actual shopping list rather than a percentage of the contractor's book price.
Thickness is the single biggest lever on cost per square foot: each added inch of slab needs more concrete and more labor to place and finish. Use matters too, since it sets a sourced default thickness (patios and sidewalks typically 4 in, garage floors 4 to 6 in, driveways 4 to 8 in per Angi's and HomeGuide's own cost guides) and a sourced reinforcement recommendation (shed pads typically need none; driveways typically need a rebar grid, per Bolsinger Rebar's own planning guidance).
A slab priced only per square foot misses real cost. Every slab needs a compacted gravel base at least 4 inches thick (ConcreteNetwork.com's own citation of ACI 302, the industry standard for concrete floor and slab construction), plus reinforcement suited to the load (wire mesh for light residential use, a rebar grid on a sourced 24 inch on-center spacing for driveways and garage floors, per Bolsinger Rebar), and a finish (broom is typically included in the base price; stamped and exposed aggregate add real cost per Angi's own finish-cost table).
For a DIYer, delivery method changes the materials cost directly: ready-mix delivered by the cubic yard usually costs less per yard for anything beyond a small pour, but carries a short-load fee below a full 10-yard truckload (HomeGuide's own concrete-pricing guide); mixing 80 lb bags yourself avoids delivery minimums entirely but costs more per cubic yard of finished concrete, and gets impractical fast on anything larger than a small pad.
Per-square-foot pricing by thickness: HomeGuide.com, "How Much Does a Concrete Slab Cost? (2026)" (February 3, 2026), whose own published thickness table (2, 4, 6, and 8 inches) fits an exact linear formula used here for every thickness, cross-checked against Angi.com, "How Much Does a New Concrete Slab Cost? [2026 Data]" (updated April 16, 2026), whose Driveway bracket runs a premium above the generic formula at the high end, disclosed rather than hidden. Materials/labor split: HomeGuide's own published 40-50 percent labor range, midpoint used. Reinforcement: Homewyse.com, "Cost to Install Wire Mesh For Concrete" (September 2026) for Wire Mesh, and Angi's own Rebar line for Rebar Grid; rebar spacing and use-based reinforcement recommendations from Bolsinger Rebar, "How to Plan and Space Rebar for Concrete Slabs". Base gravel depth: ConcreteNetwork.com, "Subgrades and Subbases for Concrete Slabs", citing ACI 302; gravel pricing reused verbatim from this site's own retaining-wall-cost-calculator (Angi's gravel-prices article). Ready-mix pricing, the short-load fee, the quarter-yard ordering increment, and the waste factor: HomeGuide.com, "How Much Does Concrete Cost Per Yard? (2026)" (January 6, 2026). Bag yield and price: Quikrete 80 lb. Concrete Mix, priced on a live Home Depot product page, yield corroborated via three independent distributor pages hosting Quikrete's own data-sheet text since Quikrete's hosted PDF does not render directly. Rebar and remesh pricing: live Home Depot product pages, priced from one Home Depot store in September 2026. Region labor multiplier reused from this site's bathroom remodel, fence, and retaining wall cost calculators, calibrated against the JLC/Zonda 2025 Cost vs Value report.
HomeGuide and Angi publish overlapping but not identical figures at the same nominal thickness: HomeGuide's per-inch formula and Angi's per-project brackets agree closely for Patio and Sidewalk, and Angi prices Driveway noticeably higher at the top end than the generic per-inch formula would suggest, both disclosed on-page in the freshness stamp above rather than silently blended away. Wire Mesh pricing is deliberately sourced to Homewyse's dedicated "wire mesh" line rather than Angi's "fiber mesh" line, since those are different materials and using the wrong one would mislabel the figure.
Building more than one thing at once? See also the Fence Cost Calculator, the Retaining Wall Cost Calculator, and the Landscaping Material Calculator for other site work estimates.