Short answer
How much cement is in 1 cubic metre of M20 concrete? One cubic metre of nominal M20 concrete (1 : 1.5 : 3) needs about 8 bags of 50 kg cement (403 kg), 0.42 m³ of sand (about 15 cft) and 0.84 m³ of coarse aggregate (about 30 cft), before wastage. Add about 5 percent for wastage on site. Leaner mixes need fewer bags, and the table below covers M5 to M20.
On this page (12)
- How much cement is in 1 cubic metre of concrete?
- What does the M5 to M20 table show?
- Why is the dry volume 1.54 times the wet volume?
- How much does one bag of cement occupy?
- Why does the table stop at M20, and what about M25?
- How do I turn the table into a quantity for my job?
- How much wastage should I add?
- Which cement should I use?
- Frequently asked questions
- Related guides
- Work out your quantities
- Sources
Need quantities? Cement, sand and aggregate calculator
Every quote for concrete rests on one number: how much cement goes into a cubic metre. Websites and contractors give different answers, from about 6 bags to about 8 bags per cubic metre of M20, because each one hides a different assumption. This page prints the assumptions, so you can check any figure against your own job.
How much cement is in 1 cubic metre of concrete?
It depends on the mix. For nominal M20 concrete, mixed 1 part cement to 1.5 parts sand to 3 parts coarse aggregate by volume, 1 cubic metre of finished concrete needs about 8.06 bags of 50 kg cement, which is about 403 kg. Leaner mixes use less: nominal M10 needs about 4.44 bags.
What does the M5 to M20 table show?
The table gives the materials for 1 cubic metre of finished (wet) concrete, with no wastage added. Sand and aggregate are shown in cubic metres and, in brackets, in cubic feet.
| Mix | Cement : sand : aggregate | Cement (50 kg bags) | Cement (kg) | Sand, m³ (cft) | Coarse aggregate, m³ (cft) |
|---|---|---|---|---|---|
| M5 | 1 : 5 : 10 | 2.77 | 139 | 0.48 (17.0) | 0.96 (34.0) |
| M7.5 | 1 : 4 : 8 | 3.41 | 171 | 0.47 (16.7) | 0.95 (33.5) |
| M10 | 1 : 3 : 6 | 4.44 | 222 | 0.46 (16.3) | 0.92 (32.6) |
| M15 | 1 : 2 : 4 | 6.34 | 317 | 0.44 (15.5) | 0.88 (31.1) |
| M20 | 1 : 1.5 : 3 | 8.06 | 403 | 0.42 (14.8) | 0.84 (29.7) |
These figures come from the From Foundation cement, sand and aggregate calculator, run with 1 m³ and 0 percent wastage. Change the wastage in the calculator to match your job.
Why is the dry volume 1.54 times the wet volume?
When cement, sand and aggregate are mixed with water, the small particles fill the gaps between the large ones, so the loose dry materials take up more space than the concrete they make. The calculator uses a factor of 1.54: to make 1 cubic metre of wet concrete you start with 1.54 cubic metres of dry materials. The cement, sand and aggregate then share that dry volume in the ratio of the mix. For M20 (1 + 1.5 + 3 = 5.5 parts) the cement share is 1.54 × 1 ÷ 5.5, or 0.280 m³.
How much does one bag of cement occupy?
The calculator treats cement as 1,440 kg per cubic metre, so a 50 kg bag is about 0.0347 m³, or about 1.23 cft. Some sites assume one bag is exactly 1 cubic foot, which makes the bag count come out about 23 percent higher than the table. Others round a bag to 1.25 cft, which is close to the table. The difference matters at the scale of a whole slab.
Why does the table stop at M20, and what about M25?
M20 is the richest grade that can be specified by simple volume proportions. IS 456 allows nominal mix concrete only up to M20. Grades above that, such as M25, are design mix concrete: the mix is worked out from trial tests on the actual materials, so there is no single bags-per-cubic-metre figure that is true everywhere. If your drawing asks for M25 or higher, ask your structural engineer or the ready-mix supplier for the mix design, and do not use a table like this one.
Lean grades such as M5, M7.5 and M10 are used where there is no reinforcement, for example as a levelling bed. Your drawing states the grade for every element, so follow it.
How do I turn the table into a quantity for my job?
Work out the volume of concrete in cubic metres (length × width × depth, all in metres), multiply by the figures in your row of the table, and add wastage. For example, 3 cubic metres of M20 with 5 percent wastage needs about 25.4 bags, which you round up to 26 whole bags. The calculator does these steps for you and shows its working.
How much wastage should I add?
The calculator starts at 5 percent, which is a common allowance for spillage, uneven surfaces and over-excavation. At 5 percent, 1 cubic metre of M20 needs about 8.47 bags, 0.44 m³ of sand and 0.88 m³ of aggregate. Careful work on a flat, well-formed job can use less, and rough excavation uses more. Ask your contractor what wastage is in their rate.
Which cement should I use?
Any of the common cements can go into nominal mix concrete, and the bag count above does not change with the type. Which type suits foundations, slabs and plaster is a separate question, covered in OPC vs PPC vs PSC cement: which one for your house?
Frequently asked questions
How many bags of cement are in 1 cubic metre of M20?
About 8.06 bags of 50 kg, or 403 kg, with no wastage. With 5 percent wastage, about 8.47 bags.
How many cubic feet is 1 cubic metre?
1 cubic metre is about 35.31 cubic feet.
What is the difference between nominal mix and design mix?
A nominal mix uses fixed volume proportions such as 1 : 1.5 : 3 and is allowed by IS 456 up to M20. A design mix is worked out by tests on the actual materials and is needed for higher grades.
Is one bag of cement equal to one cubic foot?
No. At 1,440 kg per cubic metre a 50 kg bag is about 1.23 cubic feet. Treating it as exactly 1 cubic foot raises the bag count by about 23 percent, so check which figure a quote uses.
Related guides
- Cement bags for a 1000 sq ft slab: a worked M20 example
- How many days to cure a concrete slab?
- Concrete for an isolated footing: a worked quantity example
This guide is general information and shows volumes under stated assumptions. Read the disclaimer and follow the grade and mix on your structural drawing.
Work out your quantities
- Cement, sand and aggregate calculator: Estimate cement bags, sand and aggregate for a nominal-mix concrete slab, footing or beam from its size and mix grade.
Sources
- IS 456:2000, Plain and Reinforced Concrete - Code of Practice (nominal mix concrete and minimum grades)
- IS 383:2016, Coarse and Fine Aggregate for Concrete - Specification
- IS 269:2015, Ordinary Portland Cement - Specification
General information only. It is not a structural design or professional advice. Ask a licensed structural engineer or architect to check your plans and site.