Calculate the volume of concrete needed for a slab, footing, or column from its dimensions - useful for ordering ready-mix concrete or planning a site mix.
How to Use the Concrete Calculator
Enter the "Length", "Width", and "Thickness/Depth" of one slab, footing, or column, in meters.
Enter the "Quantity" if you have multiple identical elements.
Enter a "Wastage (%)" allowance for spillage and over-excavation.
Click "Calculate Volume" to see the concrete volume needed - use this figure with the Cement Calculator to break it into cement, sand, and aggregate quantities.
The Volume Formula
Any rectangular slab, footing, beam or column is a box, so its volume is simply length × width × thickness. The calculator then multiplies by the number of identical elements and adds the wastage percentage:
Volume per unit = Length × Width × Thickness
Total volume = Volume per unit × Quantity
Volume to order = Total volume × (1 + Wastage ÷ 100)
For a column, "thickness" is its height: enter the two sides of the cross-section as length and width, and the height in the third box. Results are shown to three decimal places in cubic metres (m³).
Worked Examples
Isolated footings: a house has 6 footings, each 1.5 m × 1.5 m and 0.45 m deep. One footing is 1.5 × 1.5 × 0.45 = 1.0125 m³ (displayed as 1.012), all six come to 6.075 m³, and with 5% wastage you should plan for about 6.379 m³.
Columns: 8 columns of 300 mm × 300 mm, each 3 m tall. Enter 0.3, 0.3 and 3 with quantity 8. Each column is 0.27 m³ and the total is 2.16 m³ before wastage.
Measured in feet: a 12 ft × 10 ft slab that is 5 inches thick. Convert first: 12 ft = 3.6576 m, 10 ft = 3.048 m and 5 in = 0.127 m. The volume is 1.416 m³, which is exactly 50 cubic feet.
Converting Site Measurements to Metres
Drawings in India are usually in millimetres, while masons often measure in feet and inches. The boxes here expect metres, so convert before entering:
Measured as
Enter (m)
Concrete per 10 m² of slab
100 mm
0.100
1.00 m³
125 mm
0.125
1.25 m³
150 mm
0.150
1.50 m³
4 in
0.1016
1.016 m³
5 in
0.127
1.27 m³
6 in
0.1524
1.524 m³
1 ft
0.3048
3.048 m³
Useful factors: 1 inch = 0.0254 m, 1 foot = 0.3048 m, and 1 m³ = 35.31 cubic feet.
Getting an Accurate Estimate
Calculate each element type separately (footings, plinth beams, columns, slab) and add the totals. Where a beam is cast together with the slab, measure the beam only below the slab so the overlap is not counted twice.
Steel reinforcement takes up a small share of the volume, but it is normally ignored in estimates and treated as part of the margin.
For a round column the formula is π × radius² × height. A 300 mm diameter column, 3 m tall, holds about 0.212 m³. Work this out separately rather than entering the diameter as length and width, which would overstate it by about 27%.
Ready-mix concrete is billed per cubic metre and delivered in transit mixers of fixed capacity. Round your order sensibly and confirm the minimum quantity and part-load charges with the plant before the pour.
Footings dug in loose soil often end up wider than drawn. If the pits are already excavated, measure the actual pit size instead of using the drawing dimensions.
Frequently Asked Questions
Volume = Length × Width × Thickness, multiplied by the quantity of identical elements. All dimensions should be entered in meters to get the volume directly in cubic meters.
Real-world pours always lose some concrete to spillage, formwork leakage, and uneven excavation. A 5% wastage allowance is a commonly used rule of thumb to avoid running short mid-pour.
No, this calculator only gives you the total concrete volume. Feed that volume into the Cement Calculator with your mix ratio to get the exact cement bags, sand, and aggregate quantities.
Normal plain concrete weighs roughly 2,400 kg per cubic metre, and reinforced concrete a little more because of the steel. Multiply the volume by this figure for a rough weight, for example when checking load on a scaffold or a vehicle.
Residential roof slabs in India are commonly 125 mm to 150 mm (about 5 to 6 inches) thick, but the right thickness depends on the span, loads and support conditions. Always use the thickness shown on your structural drawing.