Concrete volume and the cement, sand and aggregate a pour needs
Runs in your browser. Nothing you type is sent anywhere. Checked against sources on 23 Oct 2026.Pouring a slab, a footing or a column and want to know what to order? Enter the length, width and thickness, pick a grade from M5 to M20, and this works out the wet volume of concrete and splits it into cement bags, sand and aggregate. The dry volume factor, the bag weight and the cement density are all boxes you can change, because each of them varies by site and by supplier.
Concrete is already chosen under Mixing; keep Measure by on Dimensions.
Choose Metres or Feet, then enter the slab Length, Width and Thickness or depth in mm.
Tap the grade chip for your mix, such as M20, so the cement, sand and aggregate parts fill in.
Read the Wet volume and Dry volume, the Sand and Aggregate in cft, and the Cement bags to buy.
Three numbers sit underneath every concrete quantity ever published, and none of them is a law of nature.
The first is the dry volume factor. Concrete is measured wet, in the shape it fills, but cement, sand and aggregate are bought dry, and dry material takes up more room than the same material once water has closed its voids. Site practice multiplies by about 1.54 for concrete and 1.33 for mortar. Neither figure is in a standard; both are conventions, quoted anywhere from 1.50 to 1.57.
The rest is a ratio. Pick a grade from M5 at 1:5:10 to M20 at 1:1.5:3 and the dry volume is divided in those proportions. Cement's share becomes kilograms and then bags; sand and aggregate stay as volumes and are shown in cubic feet as well, because that is how they are sold here, with a brass being 100 cft.
The rest of the article, and all 6 questions about Cement Calculator, are on the Cement Calculator page.
About 8.1 bags of 50 kg, which rounds up to 9 to buy. The working is one cubic metre times a dry volume factor of 1.54, divided by the 5.5 parts of a 1:1.5:3 mix, giving 0.28 cubic metres of cement at 1440 kg per cubic metre.
M20 names the strength, 20 newtons per square millimetre at 28 days, while 1:1.5:3 names the recipe that IS 456 lists as its nominal mix for that grade. One is the target and the other is the proportion of cement to sand to aggregate that usually reaches it.
Yes. Switch the mode to mortar, pick a ratio such as 1:4 for external plaster or 1:6 for brickwork, and enter the plaster area times its thickness as the volume. The aggregate part is dropped entirely and the dry factor changes to the mortar figure of 1.33.
IS 456:2000, clause 9.3, allows nominal mixes only up to M20. M25 and stronger concrete need a design mix, worked out in a laboratory from the actual aggregates and cement being used, not from a proportion written on a web page. The calculator flags a richer mix rather than quietly producing a bag count for it.
Rates and rules change; check the source before you rely on a figure.
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