Understanding Your Results
The concrete calculator provides several key outputs to help you plan and purchase materials for your project, whether it's a small footing or a large driveway.
Cubic Yards Needed
This is the primary volume measurement for ordering ready-mix concrete from a truck. The result includes the waste factor you selected. For any project larger than about 1 cubic yard, ordering ready-mix is usually more cost-effective and convenient than mixing bags by hand.
Bags Needed (60 lb & 80 lb)
For smaller projects, buying bags of concrete mix from a home improvement store is practical. The calculator estimates how many standard 60 lb or 80 lb bags you'll need to achieve the total volume required. Note that the yield per bag can vary slightly by brand, so always check the packaging.
Why is a Gravel Base Critical?
Though not part of the concrete calculation itself, almost every concrete slab requires a compacted gravel sub-base (typically 4-6 inches deep). This base provides a stable foundation, ensures proper drainage, and is the single most important factor in preventing cracks from frost heave. Do not skip this step!