Cement bags, sand and aggregate for a concrete or mortar mix, by ratio
Runs in your browser. Nothing you type is sent anywhere. Checked against sources on 23 Oct 2026.Cement Calculator splits a pour into bags, sand and aggregate. One cubic metre of M20 at 1:1.5:3 takes 8.1 bags of 50 kg, 0.42 cubic metres of sand and 0.84 of aggregate, using a dry volume factor of 1.54. Change the factor, the bag weight or the density and every figure follows.
Under Mixing, choose Concrete, or Mortar / plaster for brickwork and plastering.
Pick Dimensions to type Length, Width and Thickness or depth, or Volume to enter the wet volume.
Tap a mix ratio chip under The mix, or type the Cement parts and Sand parts yourself.
Check Weight of one bag and Wastage, and add a Price per bag if you want the cost.
Read Cement bags to buy with the sand in cft, then press Share result to send the figures.
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 second is cement's bulk density, taken as 1440 kg per cubic metre. That is a nominal figure, not a measurement of the cement in your godown. The third is the bag: 50 kg in India, 40 kg in several other countries, 94 lb in the United States.
All three are boxes on this page, with their usual values already in them and named as what they are. Change one and you can watch the bag count move, which is the most honest thing a calculator like this can show you.
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.
Mortar mode drops the aggregate and works the same way, so the dry mortar volume from the Brick Calculator can be turned into bags and sand in one step.
M20 is where the nominal mixes of IS 456 stop (clause 9.3). M25 and anything richer need a design mix from a laboratory, and the page says so rather than pretending otherwise. Nothing you type leaves your browser.
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.
Concrete is measured in its finished wet shape, but its ingredients are bought and measured dry, and dry material occupies more space. Site practice puts the increase at roughly 54 per cent for concrete and 33 per cent for mortar. No Indian standard fixes either number, which is why both are editable here.
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.
No. Water is governed by the water-to-cement ratio your mix design or your site engineer sets, and it varies with workability, weather and whether an admixture is used. Quoting a single water figure would be the sort of invented number this calculator exists to avoid printing.
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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