Cement Calculator
Calculate cement bags, sand and aggregate for a given concrete volume and mix grade (M15/M20).
Formula last reviewed 4 August 2026 · How we verify our calculators
Cement required
9 bags
- Sand
- 0.42 m³
- Aggregate
- 0.84 m³
Updates live as you type
Frequently asked questions
It depends on the volume and mix grade. The calculator applies the 1.54 dry-volume factor and the mix ratio, then converts cement volume to 50 kg bags, rounding up.
M15 uses a 1:2:4 ratio and is used for non-structural work like levelling; M20 (1:1.5:3) is stronger and used for slabs, beams and columns.
A standard cement bag in India is 50 kg. The calculator uses this to convert the required cement volume into a number of bags.
They follow the mix ratio. For M20 (1:1.5:3), every part of cement pairs with 1.5 parts sand and 3 parts aggregate by volume.
Why "1 cubic metre of concrete" needs 1.54 cubic metres of dry material
1 cubic metre of M20 concrete (ratio 1:1.5:3) doesn't need 1 m³ of dry cement, sand and aggregate — it needs 1.54 m³, because dry materials carry voids that only close once water is added and the mix compacts. Split that 1.54 m³ across the ratio's 5.5 total parts, and cement's 1-part share comes to 1.54 × (1/5.5) = 0.28 m³, converting to 9 bags (rounded up) once translated through cement's density into 50 kg units. Sand takes its 1.5-part share at 0.42 m³, aggregate its 3-part share at 0.84 m³.
Why the grade you pick changes every number downstream
M15 (1:2:4) and M20 (1:1.5:3) aren't just different labels — they're different total-part counts (7 versus 5.5), which changes cement's fractional share of the dry volume and therefore every quantity that follows. Run the same 1 m³ through M15 instead, and cement gets a smaller share of a bigger denominator — fewer bags, reflecting M15's intentionally lower-strength, lower-cement design meant for non-structural levelling work rather than load-bearing elements like slabs, beams and columns where M20 belongs.
Where this fits next to the concrete calculator
This is the materials-from-volume companion to the concrete calculator, which instead starts from slab dimensions and works forward to the same quantities. If structural drawings specify a different grade or admixtures than the two covered here, the ratios — and therefore every downstream quantity — change accordingly, so always confirm the specified grade before ordering.
This is an estimate for planning purposes. Always add a wastage margin and confirm exact quantities with your contractor or engineer before ordering materials. Real consumption varies with site conditions, mixing method and wastage — use this to plan purchases that avoid both a mid-pour shortfall and costly over-ordering of a material that hardens if left too long on site.