30 × 40 concrete slab cost
Short answer
A 30 × 40 ft concrete slab at 4" thick costs about $2,037–$2,689 in delivered ready-mix, or roughly $4,404 in 734 80-lb pre-mix bags. Ready-mix is usually cheaper once you pass about a cubic yard.
Ready-mix
$2,037–2,689
80-lb bags
$4,404
Concrete
14.81 yd³
Bags (80-lb)
734
What a 30 × 40 slab costs
The concrete for a 30 × 40 ft slab (4" thick) runs about $2,037–$2,689 delivered as ready-mix — that covers 16.3 cubic yards with waste. Buying 734 80-lb bags instead costs about $4,404, so ready-mix is the cheaper, easier choice at this size.
That's the material only. A finished 30 × 40 slab — labor, forms, a gravel base, rebar or wire mesh, and finishing — typically runs 2–3× the concrete cost, roughly $4,074–$8,067 installed. Get itemized local bids; regional labor is the biggest swing.
Watch the extras generic calculators skip: short-load fees under a full ~10 yd³ truck, pump-truck rental for hard-to-reach pours, thicker edges, and permit or inspection costs. The figure above is the concrete baseline to build a real budget on.
30 × 40 slab: cost by option
| Option | Cost | Notes |
|---|---|---|
| Ready-mix (delivered) ✓ | $2,037–$2,689 | material only · best past ~1 yd³ |
| 80-lb bags | $4,404 | 734 bags · mix yourself |
| Finished slab (installed) | $4,074–$8,067 | incl. labor, base, rebar, finishing |
✓ = cheaper material option at this size. Finished cost includes labor, base, rebar, and finishing.
What drives the cost
| Factor | Effect |
|---|---|
| Concrete volume | 16.3 yd³ with waste — the base for the cost |
| Ready-mix vs bags | $2,037–$2,689 delivered vs $4,404 in 80-lb bags; ready-mix is cheaper here |
| Short-load fee | Orders under a full ~10 yd³ truck often add a small-load surcharge |
| Thickness | A 6" driveway pour needs ~50% more concrete than a 4" slab |
| Labor & finishing | Forms, placement, and finish bring a done slab to 2–3× the material cost |
| Reinforcement & base | Rebar or wire mesh and a compacted gravel base add to the total |
| Region & permits | Local ready-mix prices and permit fees move the number |
Cost-saving tips
- Order ready-mix in the morning so you have daylight to place and finish before it sets.
- Under a full truck (~10 cubic yards)? Ask about the short-load fee up front — it can be $50–$150.
- Budget 2–3× the concrete cost for a finished slab; the material is the smaller half of the job.
- Get at least three local bids — ready-mix prices and labor rates are the biggest regional swings.
Different size or thickness?
Open the concrete calculatorOther slab sizes
Frequently asked questions
How much does a 30 × 40 concrete slab cost?
About $2,037–$2,689 for the concrete alone in delivered ready-mix (16.3 cubic yards with waste). Labor, forms, rebar, and site prep are extra — a finished slab typically runs 2–3× the material cost.
Is it cheaper to use bags or ready-mix for a 30 × 40 slab?
Buying 734 80-lb bags costs about $4,404, so ordering ready-mix is cheaper at this size. Ready-mix wins once you pass roughly a cubic yard.
What is not included in this 30 × 40 slab estimate?
Just the concrete. Excavation, gravel base, forms, wire mesh or rebar, finishing, and permits add cost. Use this as the material baseline, then get itemized bids for the full job.