How Much Concrete for a 40×60 Slab?
Quick Answer
A 40×60 foot slab poured 4 inches thick needs 29.6 cubic yards of concrete. Order about 33 cubic yards to cover a 10% waste factor. A pour this size almost always uses a 6-inch thickness for shops and pole barns, which needs about 44 cubic yards.
- 4-inch slab: 29.6 cubic yards (800 cubic feet)
- 6-inch slab (typical for shops): 44.4 cubic yards
- Order ~33 cubic yards at 4 inches with 10% waste
- Ready-mix cost: $4,445–$5,185 at 4 inches
Formula
Multiply length, width, and thickness (in feet) to get cubic feet, then divide by 27 for cubic yards. A 40×60 is 2,400 square feet, so thickness drives a large volume difference.
Step-by-Step Calculation
- 1
Slab volume in cubic feet
40 × 60 × 0.333 = 800 cubic feet
- 2
Convert to cubic yards
800 ÷ 27 = 29.6 cubic yards
- 3
Add 10% waste
29.6 × 1.10 = 32.6 → order ~33 cubic yards
- 4
At 6 inches instead
2,400 × 0.5 ÷ 27 = 44.4 cubic yards
40×60 Slab Concrete by Thickness
| Thickness | Cubic Feet | Cubic Yards | With 10% Waste | Ready-Mix Cost* |
|---|---|---|---|---|
| 4 inches | 800 | 29.6 | 32.6 | $4,445–$5,185 |
| 5 inches | 1,000 | 37.0 | 40.7 | $5,556–$6,481 |
| 6 inches | 1,200 | 44.4 | 48.9 | $6,666–$7,777 |
*Ready-mix at $150–$175 per cubic yard. Large pours often qualify for volume pricing but may need multiple truck loads scheduled back to back.
Pro Tips
- At 29.6 cubic yards (33 with waste), this is a major commercial-grade pour requiring a concrete pump truck, a crew of 8–10, and 3–4 mixer trucks staged in sequence. This is NOT a DIY project — the volume and timing demands require professional concrete contractors.
- A 40×60 slab must have expansion joints around the full perimeter plus control joints every 10–12 feet (3 across the 40-foot width, 5 across the 60-foot length). Include these in your plans before the pour — adding them after is far more expensive via concrete sawing.
- For a shop or warehouse slab this size, specify fiber-reinforced concrete ($5–$8/yard extra) in addition to rebar. The microfibers reduce surface cracking during curing and improve impact resistance for heavy equipment traffic.
- Coordinate the pour with weather forecasts — for 2,400 sq ft of exposed concrete, even moderate rain during finishing is catastrophic. Have tarps and a rain plan. Most contractors will reschedule rather than risk a ruined pour at this scale.
Key Cost Factors
- Ready-mix for 33 yards at $100–$140/yd (volume discount) runs $3,300–$4,620. Concrete pump truck: $600–$1,000 for a half-day. Rebar grid: $1,200–$1,800. Sub-base (gravel + compaction): $1,000–$1,600. Vapor barrier: $150–$250. Total materials: $6,250–$9,270.
- Professional installation for a 40×60 slab costs $12,000–$24,000 ($5–$10/sq ft). This includes forming, sub-base prep, rebar tying, pour and finish, curing compound, and sawcut joints. The per-sq-ft cost is actually lower than smaller slabs because of economies of scale — the fixed costs (mobilization, pump truck) are spread over more area.
- Permit fees for a slab this size often include plan review and may require an engineer's stamp ($500–$1,500). Most jurisdictions classify a 2,400 sq ft slab as a commercial foundation, triggering commercial building codes and inspection requirements.
Common Mistakes to Avoid
- Treating it as a single-truck pour. A 40×60 slab at 4 inches is about 29.6 cubic yards — several trucks. Poor scheduling creates cold joints between loads.
- Under-engineering. A 2,400 sq ft slab for a shop or barn needs a designed rebar grid, thickened footings, and often a specified sub-base — not a guessed thickness.
- Neglecting the sub-grade. At this scale, uniform compaction and proper drainage under the slab are critical to prevent widespread cracking and settling.
- No joint plan. Without an engineered grid of control joints, a slab this large cracks randomly.
Related Project Considerations
- Have it engineered. Load, soil, and reinforcement for a 40×60 slab should be designed by a professional, not estimated.
- Use a pump and a full crew. Placing and finishing 30 yards continuously requires a concrete pump and several experienced finishers with power trowels.
- Plan vapor barrier and thickened edges. A building slab needs a vapor barrier beneath and thickened, reinforced edges under bearing walls.
Frequently Asked Questions
How many concrete trucks for a 40×60 slab?
A full mixer holds about 10 cubic yards. A 4-inch thick 40×60 slab (33 cubic yards with waste) needs about 4 truckloads; a 6-inch slab (about 49 CY) needs roughly 5. Coordinate delivery timing with the batch plant so each truck arrives as you finish placing the previous load — a gap of more than 45–60 minutes between pours risks cold joints that crack and leak.
How thick should a 40×60 shop slab be?
Six inches is standard for shops, pole barns, and equipment storage buildings. Use rebar (#4 on 18-inch centers) or welded wire mesh for crack control. Add thickened edges (8 to 12 inches) where walls or heavy column loads bear down. For slabs holding forklifts, vehicle lifts, or heavy machinery, pour localized thick pads (8–12 inches) at the equipment anchor points rather than thickening the entire slab.
How much does a 40×60 concrete slab cost?
Materials alone run $4,400–$7,800 depending on thickness. A finished 40×60 slab poured by a contractor typically costs $14,400–$28,800 (about $6–$12 per sq ft) including grading, compacted gravel base, reinforcement, forming, labor, finishing, and control joints. Costs on the higher end reflect difficult site conditions (rocky soil, poor access) or enhanced finishes like sealed or polished floors.