Concrete Calculator
Estimate how much concrete a project needs. Choose a shape, enter dimensions, and get volume in cubic feet, yards, and meters, plus bag counts and cost.
Results
Enter your measurements to see an estimate.
Calculated: — EasyBuildTools, www.easybuildtools.com
How to use the undefined
Select the shape that matches your pour. A slab uses length, width, and thickness. A circular slab uses diameter and thickness. A footing is a long run measured by length (ft), width (in), and depth (in). A post hole uses hole diameter and depth. Set a quantity to multiply identical elements, add a waste allowance, and optionally a price per cubic yard.
Concrete is ordered by the cubic yard for ready-mix, or by the bag for small jobs. The results show both so you can decide which is more economical.
Formula and methodology
All volumes are computed in cubic feet, then converted:
- Slab: length × width × (thickness ÷ 12).
- Circular: π × (diameter÷2)² × (thickness÷12).
- Footing: length × (width÷12) × (depth÷12).
- Post hole: π × ((diameter÷12)÷2)² × depth.
Total = per-unit volume × quantity × (1 + waste% / 100). Cubic yards = cubic feet ÷ 27. Cubic meters = cubic feet × 0.0283. Bag counts assume roughly 0.45 cu ft per 60 lb bag and 0.6 cu ft per 80 lb bag, rounded up.
Worked example
Slab: 10 ft × 10 ft × 4 in thick, 10% waste. Volume = 10 × 10 × (4÷12) = 33.33 cu ft. With waste = 36.67 cu ft = 1.36 cubic yards. That is about 61 × 80 lb bags — well into ready-mix territory. Enter the values above to confirm.
Helpful measurement tips
- Order a little extra: you cannot pour half a batch later and match it.
- Compacted, level sub-base prevents thickness creep that quietly increases volume.
- For anything structural, confirm thickness and reinforcement with local code.