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Concrete Calculator
Estimate concrete volume and bag count for simple slabs, pads and small bases.
For structural work, foundations or regulated building work, check the required specification before ordering or mixing concrete.
Useful notes
What is bag yield?
Bag yield is how much mixed concrete one bag produces, usually shown in litres on the bag.
Is this suitable for foundations?
Use it for rough estimating only. Structural work needs the correct specification and depth.
Notes and next steps
How it works
Estimate concrete volume and bag count from length, width, depth and bag yield.
Estimating method: Volume = length × width × depth. Litres = m³ × 1000. Bags = ceil(litres ÷ bag yield).
Worked example
2 m × 1 m × 100 mm is 0.2 m³ or 200 L. At 12 L per bag, buy 17 bags.
Common mistakes
- Entering depth in metres instead of millimetres.
- Not allowing for uneven ground.
- Using a bag yield from a different product.