How many cubic yards of concrete do I need for a standard NB driveway?

A standard two-car concrete driveway in New Brunswick — approximately 20 feet wide by 40 feet long (800 square feet) at 5 inches thick — requires roughly 12.3 cubic yards of concrete. A more modest single-car driveway at 10 feet wide by 40 feet long (400 square feet) at the same thickness needs about 6.2 cubic yards.

The calculation is straightforward: length (feet) × width (feet) × thickness (feet) ÷ 27 = cubic yards. For thickness, convert inches to feet: 4 inches = 0.333 feet, 5 inches = 0.417 feet, 6 inches = 0.500 feet.

For a 20 × 40 driveway at 5 inches: 20 × 40 × 0.417 ÷ 27 = 12.3 cubic yards.

NB driveway thickness should be 5 to 6 inches minimum — not 4 inches. Here is why this matters for your volume calculation and your budget. The NB Building Code and sound concrete practice for vehicle traffic (passenger cars, light trucks, SUVs) calls for 5 inches as a minimum for a concrete driveway that will last. Four-inch driveways are common and may meet minimum code in some applications, but in New Brunswick's freeze-thaw climate, the extra inch of thickness adds significant resistance to cracking from frost heave and load. The incremental cost — perhaps one additional cubic yard for a typical driveway — is well worth it.

Always add 10% to your calculated volume when ordering ready-mix. This accounts for minor variations in sub-base height, spillage during placement, and the cost of not running short mid-pour. Running out of concrete during a pour forces a cold joint — a seam where fresh concrete meets concrete that has begun to set — which is a permanent weak point in the slab. It is significantly cheaper to order a half-yard more than you think you need than to deal with a cold joint or a second small delivery.

For a driveway with an attached apron that widens at the garage, a turnaround area, or any curved or irregular sections, sketch the shape and break it into rectangles or approximate shapes for your calculation. Your contractor will do this automatically, but if you are estimating for budgeting purposes, the rectangle method gives you a close approximation.

Your contractor will also account for:

• The concrete pump if one is needed (adds to labour cost but does not affect volume)


• Potential short-load surcharges if your volume falls below the 3 to 4 yard threshold where NB suppliers apply them — for the single-car driveway example above (6.2 yards), you are in a reasonable range; for a very small section, the surcharge matters

Get your contractor to specify air-entrained mix at 25 to 32 MPa for your NB driveway — this is non-negotiable for durability in our climate.