· TradeBid editorial team

Concrete Slab Cost per Square Foot and How to Bid a Slab

Work out your own concrete slab cost per square foot: concrete, base, rebar, forms, finishing and labor, plus a step-by-step way to bid a slab.

The short answer: A slab's cost per square foot is the total of concrete, base, vapor barrier, reinforcing, forms, placement, finishing, curing and markup, divided by the slab's area. National "average" numbers swing widely by region, thickness and finish, so the only number you should bid with is one built from your own supplier prices and crew rates. This guide shows how to build it.

What drives slab cost

  • Thickness: concrete volume goes up directly with it. A 6 in. slab needs 50% more concrete than a 4 in. slab.
  • Concrete mix: strength, air entrainment, fibers, accelerators and hot or cold weather additives.
  • Base and prep: gravel depth, compaction and grading.
  • Vapor barrier and insulation under the slab.
  • Reinforcing: wire mesh, rebar grid, fibers or post-tension.
  • Forms: edge forms, thickened edges and blockouts.
  • Placement: direct chute, buggies or pump.
  • Finish: broom, steel trowel, burnished, stamped, colored or polished.
  • Joints and curing: saw-cuts, sealant and curing compound.
  • Site and access: distance for trucks, slope, weather and pour size.

Step-by-step: build your slab price

Example inputs to show the method. Replace every number with your own.

1. Area and volume

  • Slab: 40 ft × 50 ft = 2,000 SF.
  • Thickness: 4 in. = 0.333 ft.
  • Volume: 2,000 × 0.333 ÷ 27 ≈ 24.7 CY.
  • Add your waste factor (say 5%), so you order about 26 CY.

2. Materials

  • Concrete: 26 CY × your supplier's delivered price per CY, plus short-load or after-hours fees if they apply.
  • Base gravel: 2,000 SF × 4 in. depth ÷ 27 ≈ 24.7 CY (or convert to tons at your supplier's rate).
  • Vapor barrier: 2,000 SF plus laps.
  • Reinforcing: wire mesh by SF, or rebar by the bar count at your spacing, converted to lbs.
  • Edge form: perimeter 180 LF.
  • Curing compound and joint sealant by SF and LF.

3. Labor

  • Base prep and compaction (SF × your rate).
  • Forming and stripping (LF × your rate).
  • Placing and finishing (SF × your rate for the finish type).
  • Saw-cutting joints (LF).
  • Use your loaded labor rate: wages plus taxes, insurance and benefits.

4. Equipment

  • Pump (if needed), power trowels, saw, compactor and any rentals.

5. Overhead and profit

6. Cost per square foot

  • Total price ÷ 2,000 SF = your price per SF for this slab.

Save that number with the job's details (thickness, finish, access). After a few jobs, you'll have your own price-per-SF ranges by slab type. That makes a good sanity check, though it doesn't replace a full takeoff.

How to bid a slab job

  1. Read the drawings and specs: thickness, mix, reinforcing, joint layout, finish, tolerances (FF/FL) and testing.
  2. Confirm your scope: excavation, grading, base, under-slab plumbing coordination and who handles testing.
  3. Do the takeoff as above, element by element, including thickened edges and footings.
  4. Price each line with current supplier quotes.
  5. Plan the pour: pour size per day, crew size, pump and weather.
  6. List exclusions: excavation, testing, winter protection, sealers, rebar supply or anything you're not doing.
  7. Send a clear proposal with base price, alternates (such as a thicker slab or a different finish), exclusions and how long the price is valid.

Common mistakes

  • Using someone else's price per SF without checking your own costs.
  • Forgetting thickened edges and turned-down slabs.
  • Missing pump costs on tight or interior pours.
  • Underpricing finish labor for high-tolerance floors.
  • No allowance for short loads on small pours.

Using software to bid concrete

With TradeBid, you upload plans or scope documents, choose Concrete, and get a draft line-item bid with quantities, labor, materials, markup and exclusions. Every line is editable, so you use your own supplier prices and crew rates and export a branded PDF proposal. Read concrete takeoff software and how to bid a concrete job, or see the sample bid.

FAQ

How do I calculate concrete for a slab? Length × width × thickness (in feet) ÷ 27 = cubic yards. Then add your waste factor.

What's a typical cost per square foot for a concrete slab? It varies a lot by region, thickness, finish and access. Build your own number from current supplier prices and your crew's production, using the steps above.

Does a thicker slab cost proportionally more? Concrete material goes up in proportion to thickness. Finishing labor goes up much less, so the total cost per SF rises by less than the thickness increase.

Should I price slabs per square foot or per cubic yard? Track both. CY drives material and placement, and SF drives finishing and prep.

What does TradeBid cost? Apprentice is $149/month (up to 5 bids), Journeyman is $300/month and Master is $850/month, or $100 for a single bid. Every plan starts with a 7-day trial. See pricing.

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