2413
Driveway calculator
Put your driveway length, width, depth and waste in: a 20 ft by 12 ft driveway at 4 in deep is 240 sq ft, 80 cu ft — 3 cu yd exact, 4 cu yd with 10% waste.
★ CONSTRUCTION · DRIVEWAYS · CONCRETE
Driveway Calculator: 4 Cu Yd for a 20x12 ft Driveway
On the defaults — a 20 ft by 12 ft driveway, 4 in deep, 10% waste — you need 4 cubic yards of concrete. This is the driveway tool: measure the driveway once, allow for the ground, and order the concrete once — a half-poured driveway waits for no second truck.
What does driveway concrete needed 4 cu yd mean?
It means four cubic yards of concrete pour a 20 ft by 12 ft driveway at 4 inches deep once waste is allowed for. The driveway itself is 240 square feet, since 20 times 12 is 240; at 4 inches deep that is 80 cubic feet, and since one cubic yard is 27 cubic feet, the exact volume is 2.96 cubic yards. With 10% waste that becomes 3.26 cubic yards, rounded up to 4 whole cubic yards because concrete is ordered by the yard, not by the fraction. The waste yard is not spare stock exactly — it is the concrete the pour consumes in spillage and uneven ground, so a driveway poured without waste runs short before the last corner.
Output · formula · meaning
| Output | Formula | What it means |
|---|---|---|
| Driveway area | length × width | 240 sq ft — 20 × 12. |
| Volume | area × (depth ÷ 12) ÷ 27 | 2.96 cu yd — 80 cu ft ÷ 27. |
| Order | volume with waste, rounded up | 4 cu yd — 3.26 cu yd, rounded up. |
Three things to check before you trust the number
First, check the depth you are actually pouring: 4 in is the standard driveway thickness, but a 6 in slab on the same driveway needs 5 cu yd with waste, and a slab poured thin cracks early. Second, remember the volume follows the area times the depth, not the length alone: a 20 ft by 12 ft driveway is 240 sq ft, and a driveway measured by one side under-orders. Third, judge the waste honestly: concrete follows the ground, so 10% fits a level, well-compacted base, but soft or uneven ground can want 15%, since every dip takes concrete. Rebar, mesh and finishing are bought separately — see the concrete driveway calculator for yards, bags and total cost on the same pour.
Worked example
20 ft long, 12 ft wide, 4 in deep, 10% waste. Area: 20 × 12 = 240 sq ft. Volume: 240 × (4 ÷ 12) = 80 cu ft, and 80 ÷ 27 = 2.96 cu yd. With waste: 80 × 1.10 = 88 cu ft, and 88 ÷ 27 = 3.26 cu yd, rounded up to 4 cu yd to order. In practice that means ordering 4 cu yd, and expecting the last yard to go on spillage and uneven ground. If the same driveway were poured 6 in deep instead, the need would rise to 5 cu yd with waste, but the driveway poured would be the same size.
Every branch, checked
With a 24 ft long driveway instead of 20 ft, the area rises to 288 sq ft and the volume to 3.56 cu yd exact, but the order stays 4 cu yd with waste, since 3.91 cu yd still fits four yards. With a 16 ft wide driveway, the area rises to 320 sq ft and the order to 5 cu yd with waste, since 4.35 cu yd needs a fifth yard. With a 6 in slab, the volume rises to 4.44 cu yd exact and the order to 5 cu yd with waste. With 0% waste, the volume stays 2.96 cu yd exact and the order falls to 3 cu yd. Driveway size, depth and waste each move the order on their own, so a wrong depth is as costly as a wrong measurement.
The reverses, worked backwards
The length behind 4 cu yd is 20 ft: at 16 ft the order is 3 cu yd (192 sq ft, 64 cu ft, 2.37 cu yd exact, 4 in deep, 10% waste); at 24 ft it is 4 cu yd (288 sq ft, 96 cu ft, 3.56 cu yd exact, 4 in deep, 10% waste). The depth behind 4 cu yd is 4 in: at 3 in the order is 3 cu yd (240 sq ft, 60 cu ft, 2.22 cu yd exact, 3 in deep, 10% waste); at 6 in it is 5 cu yd (240 sq ft, 120 cu ft, 4.44 cu yd exact, 6 in deep, 10% waste). The waste behind 4 cu yd is 10%: at 0% the order is 3 cu yd (240 sq ft, 80 cu ft, 2.96 cu yd exact, 4 in deep, 0% waste); at 20% it is 4 cu yd (240 sq ft, 80 cu ft, 2.96 cu yd exact, 4 in deep, 20% waste). Each reverse moves one input and holds the rest, so the step is exactly one dimension or one waste change.
What the defaults assume
The defaults assume a 20 ft by 12 ft rectangular driveway, a 4 in concrete slab, and 10% spillage and uneven-ground waste. They do not assume rebar, mesh, edging or finishing — a driveway that needs reinforcement counts its steel separately, and the finishing is bought by the job, not by the yard.
Who uses this
- A homeowner pouring a driveway: the 4 cu yd order settles the concrete call before the truck is booked.
- A DIY builder replacing a driveway section: the same maths on the section alone gives the yards, not a whole drive.
- A contractor quoting a job: driveway area, depth, waste — the quote follows the same three steps, and the waste line shows the client why.
- A landlord budgeting a driveway refit: the driveway size off the plans, multiplied out, gives the yard line on the refit budget.
Accuracy & limitations
The arithmetic is exact for the inputs entered; the judgement is the depth and the waste allowance. Real ground is uneven, and the slab on the ground overrides any planning figure; a driveway measured gross over-orders, and a depth read off a different job under-orders. Treat 4 cu yd as the planning order for a 20 ft by 12 ft driveway at 4 in deep, and raise the waste to 15% for soft or uneven ground.
Cite this calculator
Bright Side Kit, “Driveway Calculator: 4 Cu Yd for a 20x12 ft Driveway”, https://brightoolbox.com/driveway-calculator/, accessed 3 November 2026. Students and researchers: cite the calculator name, the page URL and the date you used it, and quote the defaults (20 ft × 12 ft, 4 in deep, 10% waste) so the 4 cu yd result can be checked.
Frequently asked questions
How many cubic yards do I need for a 20x12 ft driveway?
4 cu yd at 4 in deep with 10% waste. The volume is 80 cu ft, or 2.96 cu yd; with waste that is 3.26 cu yd, rounded up to 4.
How do I work out driveway concrete from a driveway size?
Multiply length by width for the area, multiply by depth in feet for cubic feet, divide by 27 for cubic yards, add waste and round up. A 20 ft by 12 ft driveway at 4 in is 240 sq ft, or 4 cu yd with 10% waste.
How much waste should I allow for driveway concrete?
10% for a level, well-compacted base, 15% for soft or uneven ground. Waste is the spillage and the dips, not spare stock.
Does this count rebar too?
No — this calculator counts concrete only. Rebar and mesh are counted separately, by the driveway.
Should I order the exact yards or round up?
Round up: concrete is ordered by the yard, and the spare yard is the spillage stock. A driveway poured to the exact yard runs short before the last corner.
What if my driveway is not a rectangle?
Split it into rectangles, work out each area, and add them before multiplying by the depth. The square footage calculator handles the area step section by section.