The price of a concrete slab is more than the price of the concrete. Volume is the easy part, and getting it right matters because everything else is built on it. This guide shows how to get from slab dimensions to a realistic material budget, and which line items people tend to forget.
About prices in this guide: concrete and delivery prices vary a lot by region, season and supplier, and they change over time. We have deliberately not printed “typical” prices. The dollar figures below are round example numbers to show the math, not market data. Get local quotes for your own budget.
Step 1: Calculate the volume
Multiply length × width × thickness in feet, then divide by 27 for cubic yards.
cubic yards = length (ft) × width (ft) × (thickness in ÷ 12) ÷ 27
A 24 × 24 ft slab, 4 in thick:
- Area: 24 × 24 = 576 sq ft
- Volume: 576 × 0.333 = 192 cu ft
- Cubic yards: 192 ÷ 27 = 7.11 cu yd
Thickness has a big effect on cost: the same slab at 6 in thick is 10.67 cu yd, 50% more concrete. Use the thickness your plans or local code require. Do not change it just to save money.
Step 2: Add a waste margin
Plan on ordering a bit more than the exact volume. A 5–10% margin is a common allowance for uneven subgrade, form deflection and spillage. At 10%, the example becomes 7.11 × 1.10 = 7.82 cu yd. Suppliers may round orders to a set increment, so ask how they handle it.
Step 3: Price the concrete
Ask local ready-mix suppliers for a price per cubic yard for the mix your project needs. Then multiply:
concrete cost = cubic yards to order × price per cubic yard
With an example price of $150 per yard, 7.82 cu yd comes to about $1,173. Use your own quote in theConcrete Slab Calculator to see your number.
Step 4: Add delivery and order charges
When you ask for quotes, check which of these apply. They are often listed separately from the per-yard price:
- Delivery fee, sometimes based on distance.
- Small-load or short-load fee for orders below the supplier's minimum.
- Waiting time if the truck has to wait beyond a set unloading window.
- Pump truck if the truck cannot reach the forms directly.
- Admixtures such as accelerators for cold weather, or fiber reinforcement, if specified.
Step 5: Add the materials around the concrete
A slab usually needs more than concrete. Depending on the project, budget for:
- Base material such as gravel, and compaction
- Form boards and stakes
- Reinforcement (rebar or welded wire) if your design calls for it
- A vapor barrier for some interior slabs
- Control joint tools or saw cutting, curing compound and sealer
- Tool or equipment rental: plate compactor, mixer, bull float
Step 6: Decide on labor
Placing and finishing a large slab is hard, time-critical work. Once the truck arrives, the concrete has to be placed and finished before it sets. If you hire a contractor, their quote will normally include labor, forming and finishing, and often materials, so compare total quotes rather than the concrete price alone.
A simple budget template
| Line item | How to estimate |
|---|---|
| Concrete | Cubic yards incl. waste × local price per yard |
| Delivery and fees | From your supplier quote |
| Pump (if needed) | From a pump service quote |
| Base material | Area × base depth, from supplier |
| Forms and reinforcement | Perimeter length and design, from the lumber yard |
| Finishing, curing, sealing | Product prices |
| Labor or contractor | Written quotes |
| Contingency | A buffer for surprises |
Common budgeting mistakes
- Pricing exact volume. Without a margin the budget is low before you start.
- Forgetting the fees. On a small order, delivery and short-load fees can be a large share of the total.
- Comparing different specs. Make sure every quote is for the same thickness, mix and reinforcement.
- Skipping permits. Some slabs need a permit or inspection. Your local building department can tell you.
Next steps
Enter your dimensions and local price in the Concrete Slab Calculator for an instant volume and material cost. If the slab is small, compare with bagged concrete in theConcrete Calculator, and seeHow Much Concrete Do You Need? for measuring tips.