Concrete Driveway Calculator

How it's calculated

The calculator finds the volume in cubic feet: length (ft) × width (ft) × thickness (in ÷ 12). That's converted to cubic yards by dividing by 27. A waste percentage is added on top to cover over-excavation, form loss, and cutting around an apron or transition slab, and the adjusted cubic yardage is multiplied by concrete's density to get the weight in tons. Bag counts divide the adjusted cubic feet by each bag's yield; ready-mix truckloads divide the adjusted cubic yards by the truck's capacity — for most driveways, the truckload number is the one that matters.

Worked example

A two-car driveway, 20 ft × 24 ft, poured 6 inches thick: volume = 20 × 24 × (6 ÷ 12) = 240 cubic feet. In cubic yards, that's 240 ÷ 27 = 8.89 yd³. Adding a 10% waste factor: 8.89 × 1.10 = 9.78 yd³. At 2.02 tons per cubic yard, that's 9.78 × 2.02 = 19.75 tons — or 19.07–19.85 tons across the 1.95–2.03 density range. That's just about a full ready-mix truckload (9.78 yd³ against a standard 10 yd³ capacity) — nowhere near a bagged job.

How deep should it be?

A driveway carries a fundamentally different load than a patio or walkway: the weight of a vehicle concentrated on four small tire contact patches, repeated every time it comes and goes, rather than evenly distributed foot traffic. That's why driveways are poured thicker than patios — the slab needs enough mass and support to resist point loads and flexing without cracking — and how much thicker depends on the vehicles it will see (a passenger car and a loaded delivery truck put very different loads on the same slab), the soil's bearing capacity underneath, and what your local code requires for a residential or commercial driveway. Subgrade preparation matters more here than almost anywhere else on a property: a driveway sees repeated heavy loading over years, so a well-compacted base — typically a layer of compacted gravel or crushed stone under the slab — does more to prevent cracking and settling than adding extra inches of concrete on a poorly prepared subgrade. The apron, where the driveway meets the street, and any thickened edge are frequently a separate structural detail from the rest of the driveway, sometimes governed by your municipality's own specification for work in the public right-of-way — check with your local public works or engineering department before assuming the same thickness and reinforcement apply there as the rest of the driveway. This calculator converts the area and thickness you already have into a volume and weight; it doesn't determine what that thickness or reinforcement should be.

Common mistakes

• –Using a patio's or walkway's thickness for a driveway. Vehicle loads require more mass and support than foot traffic — check your local code or a contractor's spec for the actual number rather than reusing a patio thickness.
• –Skipping proper subgrade compaction. A driveway sees repeated heavy loading for years; a poorly compacted base is a more common cause of driveway cracking than the slab being slightly thinner than ideal.
• –Assuming the apron matches the rest of the driveway. The transition at the street is sometimes a separate structural detail governed by your municipality's own right-of-way specification, not just an extension of the driveway slab.
• –Treating a driveway-sized pour as a bagged job by default. Most driveways run well past the point where ready-mix delivery is cheaper and far less labor than mixing dozens of bags by hand.
• –Pouring directly onto ungraded soil without a compacted gravel or crushed-stone base — the slab is far more likely to crack or heave under vehicle loading without one.

Where the density figure comes from

Unlike the landscape materials on this site, concrete is a manufactured product with a tightly controlled mix, so its density varies far less than gravel, sand, or mulch — and the same figure applies whether it's poured as a slab, a driveway, or any other normal-weight element. CEMEX, a major ready-mix producer, puts a solid unbroken pour at about two tons (4,000 lbs) per cubic yard. ACI 318 and ASTM C138 define normal-weight concrete at 145–150 lb/ft³ — ACI 318 uses 150 lb/ft³ as its default structural value — which works out to 3,915–4,050 lbs (1.96–2.03 tons) per cubic yard. The 1.95–2.03 ton/yd³ range here reflects that normal-weight span, not moisture variation. Lightweight and heavyweight concrete mixes fall outside this range and aren't covered by this calculator. We use 2.02 tons/yd³ as the display figure, drawn from:

• CEMEX — Ready-Mix Concrete Calculator
• ACI 318 & ASTM C138 — normal-weight concrete density, 145–150 lb/ft³

Read more in our density methodology.

FAQ

How much concrete do I need for a driveway?

For a 12 ft × 24 ft single-car driveway poured 6 inches thick, that's 12 × 24 × (6 ÷ 12) = 144 cubic feet, or about 5.33 cubic yards before waste — use the calculator above to add your waste factor and get a ready-mix order.

Why are driveways poured thicker than patios?

A driveway carries concentrated, repeated loads from vehicle tires instead of evenly distributed foot traffic, so it needs more mass and support to resist cracking and flexing under that load. A patio or walkway that only ever sees people walking on it doesn't face the same stress.

What determines how thick my driveway should be?

The vehicles it will carry, your soil's bearing capacity, and your local code's requirements for a residential or commercial driveway. This calculator doesn't set that number for you — check your local building department or a contractor's spec for the figure that applies to your project.

Does the apron need a different thickness than the rest of the driveway?

Possibly. The apron, where the driveway meets the street, is sometimes governed by your municipality's own specification for work in the public right-of-way, separate from the driveway's own design. Check with your local public works or engineering department before assuming the two match.

How important is subgrade preparation for a driveway?

Very. A driveway sees repeated heavy loading over years, and a well-compacted gravel or crushed-stone base does more to prevent cracking and settling than adding extra inches of concrete on top of a poorly prepared subgrade.

Should I use bags or ready-mix for a driveway?

Almost always ready-mix — most driveways need several cubic yards, well past the point where ready-mix delivery is cheaper and far less labor than mixing bags by hand. Bags make sense for a small patch or repair, not a full driveway pour.

How many ready-mix truckloads will I need?

Divide your adjusted cubic yardage by the truck's capacity — standard ready-mix trucks carry about 10 cubic yards per full load. The calculator above uses 10 cubic yards as a default and rounds up, since a partial load still requires dispatching a truck, and most plants charge extra for small or split loads.