Concrete calculator
Calculate the volume of concrete for a slab, footing, beam or subfloor and how many bags of cement, sand and gravel to buy for the mix ratio.
How to useHow much concrete do I need?
Estimate for small projects. Structures must follow an engineer’s design.
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Concrete calculator: what it is for
Enter the dimensions and number of pieces to calculate the concrete volume in m³. Choose the mix (1:2:3, 1:2.5:3.5, 1:3:5 or 1:3 mortar) and see the bags of cement, the sand and the gravel in m³ and in 18-liter cans, plus the approximate water.
The calculation uses a factor of 1.54 for the dry volume of the materials.
How to use
- Type the length, width and thickness.
- Choose the mix and the waste.
- See the cement, sand, gravel and water.
When to use it
- Pour a slab, sidewalk or subfloor.
- Make footings and beams for small projects.
- Buy the right materials at the hardware store.
Frequently asked questions
How are the materials calculated?
The volume is multiplied by 1.54 (dry materials take up more space than finished concrete) and divided by the parts of the mix. Cement is converted into 50 kg bags assuming 1,440 kg per m³.
Which mix should I use?
1 : 2 : 3 is common for slabs, beams and columns in small projects; 1 : 2.5 : 3.5 for footings and floors; 1 : 3 : 5 for subfloors and sidewalks with no structural role. For structures, follow the engineer's design.
What is an 18-liter can?
It is the measure used on site in Brazil to portion sand and gravel, about the size of a 5-gallon bucket. The calculator also shows the materials in cans.
Is it really free?
Yes, 100% free. No sign-up, no subscription and no usage limits. All Tools123 tools are free and run right in your browser.