Ready-mix concrete calculator
Concrete volume is the shape's volume in cubic metres plus a waste allowance. Divide that total by the truck capacity and round up to count loads. For site mixing, multiply the total by 1.54 and split it by the mix ratio into cement, sand and aggregate.
Volume for each shape
Pick a shape and fill in the boxes it uses. A slab or strip footing is length x width x depth. A rectangular column is length x width x height x number of columns. A circular column is pi x (diameter / 2)^2 x height x number of columns. A wall is length x thickness x height. All dimensions are in metres, so the result is in cubic metres.
The waste allowance is added as total = volume x (1 + waste %). The 5% in the box is an example that you should change to suit the job. Allowances of 5 to 10% are commonly suggested for spillage, uneven ground and over-filling, so that a pour does not run short.
Truck loads
Truck loads = ceil(total / truck capacity). The default capacity of 8 m3 is only an example in the box. Your supplier decides what trucks it sends and in what sizes, so enter the capacity it confirms. Because the result is rounded up, the last truck is usually part-loaded, and the calculator shows whole loads only. Bagged concrete tends to suit very small pours, and ready-mix delivered by truck the larger ones.
Receiving the concrete is part of site control. Record each delivery against the order, and in site stores a goods received note records what arrived. The procurement guide and landed cost explain pricing what you buy.
Site-mixed concrete
For mixing on site, pick a nominal mix of 1 : 2 : 4 or 1 : 1.5 : 3 (cement : sand : aggregate by volume). The dry volume of materials is taken as 1.54 times the volume of wet concrete, a common estimating factor, and is shared out by the parts in the ratio. For 1 : 2 : 4 there are 7 parts, so cement is 1/7, sand 2/7 and aggregate 4/7 of the dry volume.
The result is a quantity estimate in cubic metres, not a mix design, and it does not state any grade or truck size. Follow your engineer's specification. Enter a price per cubic metre and the calculator multiplies it by the total to give a cost before VAT. See the VAT calculator, the retention calculator and the payment certificate calculator for how it flows into a claim. Inspections of concrete work are covered under quality and handover, the work inspection report and the material inspection report.
Worked example
A slab 10 m long, 6 m wide and 0.15 m deep, with 5% waste, an 8 m3 truck and a 1 : 2 : 4 site mix.
| Step | Working | Result |
|---|---|---|
| Volume | 10 x 6 x 0.15 | 9.00 m3 |
| With 5% waste | 9.00 x 1.05 | 9.45 m3 |
| Truck loads | ceil(9.45 / 8) = ceil(1.18) | 2 |
| Dry volume | 9.45 x 1.54 | 14.55 m3 |
| Cement (1 part of 7) | 14.553 / 7 | 2.08 m3 |
| Sand (2 parts) | 14.553 x 2 / 7 | 4.16 m3 |
| Aggregate (4 parts) | 14.553 x 4 / 7 | 8.32 m3 |
Worked example
A slab 10 m x 6 m x 0.15 m is 9.00 m3. With 5% waste the total is 9.45 m3, which needs ceil(9.45 / 8) = 2 truck loads of 8 m3. If mixed on site at 1 : 2 : 4, the dry volume is 9.45 x 1.54 = 14.55 m3, giving cement 2.08 m3, sand 4.16 m3 and aggregate 8.32 m3 (14.553 shared in sevenths, shown rounded). At an example price of AED 450 per m3 the 9.45 m3 costs AED 4,252.50.
Questions people ask
How do I calculate concrete for a slab?
Multiply length x width x depth in metres to get cubic metres, then add a waste allowance.
How much waste should I allow?
The 5% in the box is an example. Allowances of 5 to 10% are commonly suggested. Set your own.
How many truck loads do I need?
Divide the total by the truck capacity your supplier confirms and round up.
Is 8 m3 a standard truck size?
No. 8 m3 is only an editable example. Use the capacity your supplier gives you.
What does the 1.54 factor do?
It converts the volume of wet concrete into the volume of dry materials needed, as a common estimating allowance.
What do the mix ratios mean?
Parts of cement : sand : aggregate by volume, for example 1 : 2 : 4.
Does the tool give cement in bags?
No. It gives cubic metres, because bag sizes and cement density vary.
Does it give a concrete grade?
No. It estimates quantities only. Grades and mixes come from the specification.
Is the cost before VAT?
It multiplies the price you enter by the total volume, so it is as inclusive or exclusive of VAT as the price.
Can I use it for columns?
Yes. Choose a circular or rectangular column and enter the size, height and number of columns.