How Much Concrete Do I Need for a Driveway?
A typical single-car driveway (12 × 24 ft) at 4 inches thick needs about 3.6 cubic yards of concrete, or about 4 yards once you add a safety margin. A two-car driveway (24 × 24 ft) needs about 8 yards. Here is how to work out your own number, or plug your size into the concrete calculator.
The formula
cubic yards = length (ft) × width (ft) × thickness (in) ÷ 12 ÷ 27
Then add 5–10% for an uneven base and spillage. Ready-mix is sold by the cubic yard, usually in quarter- or half-yard steps, so round up.
Concrete for common driveway sizes
| Driveway | 4 in thick | 5 in thick | 6 in thick |
|---|---|---|---|
| Single car, 12 × 24 ft | 3.6 yd (order 4) | 4.4 yd (order 5) | 5.3 yd (order 6) |
| Single car, long, 12 × 40 ft | 5.9 yd (order 7) | 7.4 yd (order 8.5) | 8.9 yd (order 10) |
| Two car, 24 × 24 ft | 7.1 yd (order 8) | 8.9 yd (order 10) | 10.7 yd (order 12) |
| Two car, 20 × 40 ft | 9.9 yd (order 11) | 12.3 yd (order 14) | 14.8 yd (order 16.5) |
"Order" amounts include about 10% extra, rounded up to the next half yard.
How thick should a driveway be?
- 4 inches: the usual minimum for passenger cars on well-compacted soil.
- 5 inches: a common upgrade that adds a lot of strength for about 25% more concrete.
- 6 inches: for pickup trucks, RVs, delivery vehicles or soft, clay-heavy soil.
Make the edges a little thicker than the middle if heavy vehicles will drive near them; edges crack first.
Don't skip the base
Concrete is only as good as what's under it. Most driveways sit on 4–6 inches of compacted gravel (crushed stone or "crusher run"). For a 12 × 24 ft driveway, 4 inches of base is about 3.6 cubic yards, roughly 5 tons. The gravel calculator works this out for any size.
Reinforcement and joints
- Rebar or wire mesh helps hold cracks together. #3 or #4 rebar on a grid of about 18–24 inches is common for driveways; keep it in the middle of the slab on chairs, not lying on the ground.
- Control joints tell the slab where to crack. A common rule is a spacing (in feet) of 2–3 times the thickness (in inches): every 8–12 ft for a 4 inch slab, cut to a quarter of the slab's depth.
- Air-entrained concrete resists freeze-thaw damage. Ask for it in cold climates, along with a 4,000 psi mix.
Ordering ready-mix
Give the supplier your cubic yards, the strength (psi), and whether you need air entrainment. Ask about short-load fees, which many suppliers charge on small orders, and how long the truck can wait before overtime charges start. Have the forms, base and reinforcement inspected and ready before the truck arrives: a driveway pour moves fast.
Prices vary widely by region. Get quotes from two or three local suppliers and confirm delivery and short-load charges up front.