Construction
Concrete Calculator
How much concrete do you actually need? Pick the shape, plug in dimensions, and get cubic yards, cubic meters, and a bag count — with optional waste factor.
Pick a shape and enter dimensions.
Rules of thumb
- A standard residential slab is 4 inches thick. Driveways often go 5–6 inches.
- Always order with a 10% waste factor at minimum — spillage, uneven subgrade, formwork over-pour.
- One 80 lb bag ≈ 0.6 ft³ of mixed concrete. One 60 lb bag ≈ 0.45 ft³.
- For anything over ~1 yd³, ready-mix delivery is cheaper than bags. Below 1 yd³, bags win.
FAQ
How accurate is this? +
The math is exact. The 10% waste factor is industry standard — you can adjust it. Bag counts round UP because you can't buy half a bag.
What's the difference between concrete and cement? +
Cement is one ingredient. Concrete is the mix: cement + sand + aggregate + water. This calculator is for finished concrete volume.
When should I order ready-mix vs bags? +
Roughly: under 1 cubic yard, bags. Over 1 cubic yard, ready-mix delivered. A truck holds ~10 yd³ and has a minimum order in most areas.