Concrete quantity calculator for footings, columns and slabs
Concrete quantity = the sum of the element volumes: length × width × height for footings, beams and rectangular columns, area × thickness for slabs, and π × radius² × height for circular columns, plus a waste allowance. The calculator also gives cement bags, sand and gravel from default ratios you can change to match your mix.
Calculator
- Concrete including waste
- 45.06 m³
- Net volume
- 42.91 m³
- Rectangular / slabs / circular columns
- 18 / 22.5 / 2.41 m³
- Cement
- 316 bags
- Sand / gravel
- 20.28 / 38.3 m³
Method, step by step
- Volume of one rectangular element = length × width × height; multiply by the number of identical elements.
- Slab volume = area × thickness; multiply by the number of identical slabs (for example, floors).
- Circular column volume = π × (diameter ÷ 2)² × height; multiply by the number of columns.
- Add the volumes for the net volume, then multiply by (1 + waste ÷ 100).
- Cement = volume including waste × 350 kg ÷ 50 kg per bag, rounded up; sand = volume × 0.45; gravel = volume × 0.85.
Worked example
Inputs
- Length (m): 2
- Width (m): 1.5
- Height or depth (m): 0.6
- Number of rectangular elements: 10
- Slab area (m²): 150
- Slab thickness (m): 0.15
- Number of identical slabs: 1
- Circular column diameter (cm): 40
- Circular column height (m): 3.2
- Number of circular columns: 6
- Waste %: 5
- Rectangular elements = length × width × height × count = 2 × 1.5 × 0.6 × 10 = 18 m³.
- Slabs = area × thickness × count = 150 × 0.15 × 1 = 22.5 m³.
- Circular columns: radius = 40 ÷ 200 = 0.2 m, volume = π × 0.2² × 3.2 × 6 = 2.41 m³.
- Net volume = 18 + 22.5 + 2.41 = 42.91 m³; with 5% waste, 42.91 × (1 + 5 ÷ 100) = 45.06 m³.
- Cement = 45.06 × 350 ÷ 50 = 316 bags, rounded up.
- Sand = 45.06 × 0.45 = 20.28 m³; gravel = 45.06 × 0.85 = 38.3 m³.
Result
- Concrete including waste
- 45.06 m³
- Net volume
- 42.91 m³
- Rectangular / slabs / circular columns
- 18 / 22.5 / 2.41 m³
- Cement
- 316 bags
- Sand / gravel
- 20.28 / 38.3 m³
Assumptions and default ratios
| Ratio | Default value |
|---|---|
| Cement in concrete | 350 kg/m³ |
| Cement bag weight | 50 kg/bag |
| Sand ratio | 0.45 m³ per m³ of concrete |
| Gravel ratio | 0.85 m³ per m³ of concrete |
- Leave any group at 0 if it is not part of your take-off, to calculate only footings or only a slab, for example.
- Volumes are plain geometry from the sizes you enter: the calculator does not deduct where beams meet slabs or columns, so do not enter a shared part twice.
- The defaults are the reinforced-concrete ratios common in Egyptian specifications: 350 kg of cement per m³ for slabs, beams, columns and footings. Plain and blinding concrete usually take 250 kg of cement per m³: change the cement ratio under «edit ratios». Every ratio is editable and follows the concrete mix approved for your project.
- The waste percentage is an allowance the engineer sets for the pouring method and site conditions.
Frequently asked questions
How do I calculate the concrete for a slab?
Multiply the slab area in square metres by its thickness in metres. A 150 m² slab, 15 cm thick, needs 150 × 0.15 = 22.5 m³ before waste.
How many bags of cement are in one cubic metre of concrete?
With the default 350 kg of cement per cubic metre and 50 kg bags: 7 bags per cubic metre. Change the ratio under the editable ratios if your mix differs.
How do I calculate the concrete in a circular column?
Column volume = π × radius² × height. A 40 cm column, 3 m high: π × 0.2² × 3 = about 0.377 m³.
Why add a waste allowance?
Some concrete is lost in transport and placing and to tolerances in sizes and formwork, so a little more than the net volume is ordered. The calculator shows the net volume and the volume including waste together.
Add the result to your project BOQ in Ta3mir
In Ta3mir the same calculators work inside your project: send a result to a BOQ line in one click and save your own default ratios for every calculation.