BuildCalc Guides · Concrete
How Many Bags of Concrete for a Driveway?
The short version: don't. A driveway is the volume that breaks the bag math. Here is the real number, the ready-mix math, and how to think about size, thickness and cost.
The math
Same formula as any slab — length × width × depth in feet, then convert. For a 12 × 40 × 4 in driveway:
- Cubic feet = 12 × 40 × (4 ÷ 12) = 160 ft³.
- Cubic yards = 160 ÷ 27 = 5.93 yd³ net.
- Order amount = 5.93 × 1.05 = 6.2 yd³ with 5% waste. Most suppliers sell in 0.25 yd³ increments, so order 6.25 yd³.
- Equivalent bag count: 160 ÷ 0.6 = ~267 bags of 80 lb (or 356 bags of 60 lb). At ~50 pounds per bag handled twice (lift, mix), that is 13 tons of moving — and the cold joints between batches will crack.
By driveway size
Cubic yards for common driveway dimensions at three slab thicknesses. Add 5 to 10 percent to the order to cover waste and over-excavation.
| Driveway | sq ft | 4 in (yd³) | 5 in (yd³) | 6 in (yd³) |
|---|---|---|---|---|
| 10 × 20 ft (1-car short) | 200 | 2.5 | 3.1 | 3.7 |
| 12 × 40 ft (1-car standard) | 480 | 5.9 | 7.4 | 8.9 |
| 16 × 40 ft (1.5-car) | 640 | 7.9 | 9.9 | 11.9 |
| 20 × 40 ft (2-car standard) | 800 | 9.9 | 12.3 | 14.8 |
| 24 × 40 ft (2-car wide) | 960 | 11.9 | 14.8 | 17.8 |
Net volumes. Add 5 to 10 percent for waste. 5 inch is the sweet spot for most residential driveways.
Why ready-mix wins on driveways
- Cold joints crack. A driveway poured in 12 batches from a wheelbarrow has 11 cold joints between batches. Each one becomes a future crack line. A ready-mix truck delivers it monolithically in 30 to 45 minutes.
- Bag mix is weaker. Most bagged concrete is rated 4,000 psi but actually tests in the 3,000 to 3,500 psi range when hand-mixed. Ready-mix from a plant is consistent and quality-controlled.
- Cost is similar or cheaper. At 6 yd³, bagged concrete is $1,200 to $1,500 in material. Ready-mix at $175/yd³ is about $1,050 plus a $100 to $200 short-load fee — total $1,150 to $1,250. Plus you finish in one afternoon instead of three days.
- Finishing window. A good driveway finish (broomed, sealed, edged) requires the whole slab to be at similar set-time. That only happens with one pour.
Pour-day plan
- Day 1: excavate to depth (slab + 4 inches of gravel base), form the perimeter, compact the subgrade.
- Day 2: place 4 inches of crushed stone, compact in 2-inch lifts, lay rebar or wire mesh on chairs.
- Day 3 (pour day): truck arrives, pour, screed, bull-float, broom finish, control joints every 10 to 12 ft, edge.
- Day 4 to 7: keep wet with sprinkler or curing blanket. No foot traffic for 24 hours, no vehicle traffic for 7 days.
Calculate for your own driveway
Punch in length, width and thickness — BuildCalc returns cubic yards, the ready-mix order amount with waste factored in, and the equivalent bag count if you really want to know.
Open the concrete calculator →FAQ
Can I pour a driveway with bagged concrete?+
Technically yes — but for a single-car driveway you would mix 250 to 300 bags of 80 lb, which is 10+ hours of mixing and the cold joints between batches will crack. Anything bigger than about 3 yards (a small slab) should go ready-mix. Driveways are 5 to 12 yards.
How many cubic yards of concrete do I need for a driveway?+
A standard 1-car driveway (12 × 40 ft, 4 in thick) is about 5.9 yd³. A 2-car driveway (20 × 40 ft, 4 in) is about 9.9 yd³. Step up to 6 inches and those numbers go to 8.9 and 14.8 yd³. Add 5 to 10 percent for waste and over-excavation.
How thick should a concrete driveway be?+
4 inches handles passenger cars and light trucks. 5 inches is the sweet spot for most homes. 6 inches is standard if you ever park an RV, dump trailer, or work truck. Subgrade prep matters as much as thickness — 4 inches of compacted gravel base under the concrete prevents differential settlement.
How much does a concrete driveway cost?+
Materials alone for a 1-car (12 × 40 × 4 in) driveway are about $900 to $1,200 of ready-mix at $150 to $200 per yard. Installed by a contractor, that same driveway runs $5 to $10 per sq ft = $2,400 to $4,800. DIY saves the labor but doubles the schedule and risks cracking if you mix from bags.
Do driveways need rebar or wire mesh?+
Yes. Use #4 rebar at 12 to 18 inch on-center (a grid) or 6×6 W2.9/W2.9 welded wire mesh. Chair it up so it sits in the middle of the slab thickness. Rebar does not stop cracks from happening — it stops the two sides of a crack from drifting apart and creating a trip hazard.
How long until you can drive on a new concrete driveway?+
Foot traffic at 24 to 48 hours. Cars at 7 days (most ready-mix is rated 28-day strength but reaches 70 percent in a week). Heavy trucks or RVs at 28 days. In cold weather (below 50°F) double those numbers. Keep it wet or covered the first 7 days — that is what builds long-term strength.
Related guides
- How many bags of concrete for a 20×20 slab? — garage-floor sized pour, where ready-mix also wins.
- How many bags of concrete in a yard? — the conversion you need when comparing prices.
- How many yards of gravel for a driveway? — for the base under the slab.