Key Takeaways
- Driveway volume uses the same length x width x thickness formula as a slab
- Ready-mix trucks carry a fixed maximum load, commonly around 9 cubic yards
- Control joints give concrete a planned place to crack instead of a random one
- Joint spacing is commonly 2 to 3 times the slab thickness in inches, in feet
A driveway pour is usually too large for bagged concrete, which shifts the planning question from bag counts to ready-mix logistics: how many cubic yards, and how many truck loads does that become.
Volume, then truck loads
The volume calculation itself is the same as any slab: length times width times thickness. A 20 by 10 foot section at 4 inches thick, with a 10 percent waste allowance, comes to about 2.72 cubic yards, which fits comfortably in one truck load. Ready-mix trucks carry a fixed maximum, commonly around 9 cubic yards for a standard mixer, so any pour is rounded up to whole truck loads: 9.5 cubic yards still needs two trucks, not one and a half.
Why control joints matter
Concrete shrinks slightly as it cures, and it will crack somewhere. A control joint, cut or tooled into the surface at a regular interval while the concrete is still workable, gives that shrinkage a planned, straight place to crack instead of leaving it to crack randomly across the slab. Without control joints, a driveway typically still cracks, just unpredictably and less tidily.
Choosing joint spacing
A commonly used starting point is spacing in feet of roughly two to three times the slab thickness in inches, so a 4 inch driveway often uses joints every 8 to 12 feet. Climate, the subgrade underneath, and the specific concrete mix all affect the ideal spacing for a given job, which is why this is a planning guideline rather than a fixed rule; a concrete contractor familiar with local conditions can refine it.
Planning the pour day
Knowing the truck load count in advance matters for more than budgeting: it affects how the pour day is scheduled, since consecutive truck loads need to be placed and finished before the earlier concrete starts to set, especially in hot weather.
Use the concrete driveway calculator to work out volume, estimated control joint count and truck loads for your own driveway dimensions. For a smaller single slab such as a patio, see the concrete slab calculator, and if the driveway sits on a gravel base, the gravel driveway calculator covers that layer separately.