Concrete Calculator
Calculate concrete volume for a slab in m³ and yd³, plus the number of pre-mix bags required.
How to use it
- Enter the slab size Length, width and depth in metres.
- Add the bag yield The m³ one bag fills, from the bag label.
- Read the volume Volume in m³ and yd³, plus bag count.
Examples
| 2×2×0.1 m | 0.4 m³ |
|---|---|
| 0.011/bag | ~37 bags |
About this tool
Pouring a slab, footing or path starts with knowing the volume of concrete required. This calculator multiplies the length, width and depth to give the volume in both cubic metres and cubic yards, and works out how many pre-mix bags that takes.
Enter the yield printed on your chosen bag for a bag count, and order a little extra to allow for spillage and uneven ground. The calculation runs entirely in your browser.
Frequently asked questions
How do I find a bag's yield?
It's usually printed on the bag — a 25 kg bag of pre-mix yields roughly 0.011 m³ of set concrete.
Should I order extra?
Yes. Add about 5–10% for spillage and uneven ground so you don't run short mid-pour.
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Updated June 14, 2026