Our concrete calculators turn your dimensions into the numbers you actually order: cubic yards for ready-mix, the count of 40, 60, or 80 lb bags, the rebar grid, and a national-average material cost. Every tool shows the formula it uses (volume = length × width × thickness, divided by 27 for cubic yards) and applies a sensible waste allowance so you do not run short mid-pour.
Start with the concrete slab calculator for patios, driveways, and garage floors, or the general concrete calculator for footings and round forms. Use the column calculator for piers and tubes, the cement calculator for mix-ratio batching, and the rebar calculator to size the reinforcing steel.
For worked examples and pro tips, read How to Estimate Concrete and the in-depth Concrete Slab Estimating guide, or browse 200 answered questions in the concrete FAQ. Bag yields follow ASTM C387 (0.30 / 0.45 / 0.60 ft³ for 40 / 60 / 80 lb) and volumes follow standard ACI practice.