Concrete Driveway Calculator
Works out the concrete for a driveway at vehicle-rated thickness. A driveway is the one slab most people under-order, because the thickness that carries a car is half again what a patio needs.
Includes the waste allowance — this is the figure to order.
Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.
The formula
volume = length × width × thickness × (1 + waste)
A slab is a rectangular prism, so the volume is the three dimensions multiplied together. The only judgement in it is the waste allowance — concrete cannot be topped up once it starts curing, so under-ordering is far more expensive than over-ordering.
What to watch out for
A driveway is not a thick patio — it carries a moving load, and that changes three things:
- 150 mm (6 in) is the floor for cars, 200 mm (8 in) if anything heavier will park or turn on it. At 100 mm you will get cracking within a few winters.
- The sub-base does most of the work. 150 mm of compacted hardcore under the slab matters more than another 25 mm of concrete on top, and costs a fraction as much.
- Reinforcement is normal here. A384 mesh or fibre-reinforced mix; the calculator gives the concrete volume either way, since mesh displaces almost nothing.
- Falls and drainage. A driveway needs a slight slope away from the building — usually 1:60 to 1:80 — and in many places new hard surfaces need to drain to a permeable area rather than the road.
Frequently Asked Questions
How thick should a concrete driveway be?
150 mm (6 in) for cars and light vans. 200 mm (8 in) where a motorhome, boat trailer or delivery lorry will run on it. Thinner than 150 mm is a patio specification and will crack under a vehicle.
How much concrete for a two-car driveway?
A typical 6 × 6 m two-car driveway at 150 mm needs about 5.4 m³ before waste — roughly 7 cubic yards. That is a full ready-mix delivery with no short-load fee.
Do I need mesh or rebar in a driveway?
Reinforcement is standard. A142 or A193 mesh in the middle third of the slab, or a fibre-reinforced mix. It does not change the volume you order — mesh displaces a negligible amount.
How long before I can drive on it?
Foot traffic after 24–48 hours; cars after 7 days; heavy vehicles after 28 days, when the mix reaches its design strength. Driving on it early is the most common way a good pour gets ruined.