Concrete volume calculator
Pick the shape and type the sizes: you get the cubic metres of concrete, with a margin, and the number of ready-mix bags.
Result
1.26 m³Concrete to order
- Exact volume (no margin)
- 1.2 m³
- 25 kg bags (≈ 11.6 L each)
- 109
- Or 35 kg bags (≈ 16.3 L each)
- 78
- Weight of dry mix
- 2,709 kg
Inputs
- Shape
- Slab
- Length
- 4
- Width
- 3
- Thickness
- 10
- Margin for waste
- 5
- Price per m³ (optional)
- 0
How it is calculated
Slab: length × width × thickness. Footing: length × width × depth.
Result
Concrete to order
- Exact volume (no margin)
- 1.2 m³
- 25 kg bags (≈ 11.6 L each)
- 109
- Or 35 kg bags (≈ 16.3 L each)
- 78
How it is calculated
- Slab: length × width × thickness. Footing: length × width × depth.
- Round column: π × radius² × height × number of columns.
- Solid stairs: each step is a block; volume = width × depth × height × n(n+1)/2.
- Add the margin, then: bags = volume ÷ yield of one bag, rounded up.
- Yield used: about 2,150 kg of dry mix per m³, so ≈ 11.6 L per 25 kg bag.
Example
A 4 m × 3 m × 10 cm slab: 1.2 m³. With a 5% margin: 1.26 m³, so 109 bags of 25 kg.
Good to know
- This is a guide for ordering: check on site and on the bag label.
- Bag yield depends on the brand. Above about 1 m³, a ready-mix truck is often easier.
- Steel bars, formwork and concrete strength are not calculated.
Frequently asked questions
What is this tool used for?
Pick the shape and type the sizes: you get the cubic metres of concrete, with a margin, and the number of ready-mix bags.
How is the result calculated?
Slab: length × width × thickness. Footing: length × width × depth.
What should I check before using the result?
This is a guide for ordering: check on site and on the bag label.