Concrete Mix Ratio Calculator
Pick a grade or type your own ratio, enter the volume or the size of your slab or column, and get the cement bags, sand, aggregate and water, how much to put in each mixer batch, and the cost.
1Compare
Your volume in every grade
The same concrete worked out in each nominal mix, with your rates, so you can see what a higher grade costs.
| Grade | Mix | Cement bags | Sand cum | Aggregate cum | Water L | Total | Per cum |
|---|---|---|---|---|---|---|---|
| M5 | 1:5:10 | 10 | 1.71 | 3.42 | 300 | ₹20,836 | ₹5,981 |
| M7.5 | 1:4:8 | 13 | 1.68 | 3.37 | 390 | ₹21,841 | ₹6,269 |
| M10 | 1:3:6 | 16 | 1.64 | 3.28 | 440 | ₹22,729 | ₹6,524 |
| M15 | 1:2:4 | 23 | 1.56 | 3.13 | 633 | ₹24,951 | ₹7,162 |
| M20 | 1:1.5:3 | 29 | 1.49 | 2.98 | 725 | ₹26,825 | ₹7,700 |
| M25 | 1:1:2 | 40 | 1.37 | 2.74 | 900 | ₹30,305 | ₹8,699 |
2On site
What goes into one bag of cement
Site mixing is done by the bag. A 35 litre gauge box (farma) holds about the same volume as one 50 kg bag, so the ratio numbers tell you how many boxes of sand and aggregate to add.
| Grade | Sand per bag | Aggregate per bag | Gauge boxes | Water per bag | Concrete per bag |
|---|---|---|---|---|---|
| M5 (1:5:10) | 6.13 cft | 12.25 cft | 1 : 5 : 10 | 30 L | 0.361 cum |
| M7.5 (1:4:8) | 4.90 cft | 9.80 cft | 1 : 4 : 8 | 30 L | 0.293 cum |
| M10 (1:3:6) | 3.68 cft | 7.35 cft | 1 : 3 : 6 | 28 L | 0.225 cum |
| M15 (1:2:4) | 2.45 cft | 4.90 cft | 1 : 2 : 4 | 28 L | 0.158 cum |
| M20 (1:1.5:3) | 1.84 cft | 3.68 cft | 1 : 1.5 : 3 | 25 L | 0.124 cum |
| M25 (1:1:2) | 1.23 cft | 2.45 cft | 1 : 1 : 2 | 23 L | 0.090 cum |
3Grades
Nominal mix or design mix: which grade can you make on site?
The grade is the strength after 28 days in N/mm². Nominal ratios are a safe, simple way to reach low and medium grades on site; above M20 a lab design mix or ready-mix concrete is the reliable route.
M5 and M7.5
1:5:10 · 1:4:8Use for: lean concrete below footings, levelling and filling.
Not for: anything that carries load or has steel.
M10 and M15
1:3:6 · 1:2:4Use for: PCC under floors, paths, steps, plain concrete floors.
Not for: slabs, beams or columns.
M20
1:1.5:3Use for: RCC slabs, beams, columns and footings of houses in mild conditions.
Watch: the highest grade allowed by nominal mix under IS 456.
M25
1:1:2 as a guideUse for: RCC exposed to rain, soil or water, taller buildings.
Watch: order as design mix or ready-mix; the ratio here only estimates quantity.
The drawings decide the grade. Use the grade your structural engineer specified; a richer ratio on site cannot make up for poor curing or too much water.
4Method
How the quantities are worked out
The dry volume method used on Indian sites.
- Volumes, not weights. Nominal ratios are by volume. Design mixes use weights and need a lab.
- Moist sand bulks. Damp sand takes up to a quarter more space, so add more by volume when it is wet.
- Steel takes little room. Reinforcement is 1 to 2% of volume and is covered by wastage.
5Scope
What this calculator does and does not do
Knowing the limits helps you add the right margin before you place an order.
✓It does
- Work out cement, sand, aggregate and water for any grade or ratio
- Find the volume of slabs, rectangles and round columns
- Tell you what to add to each bag and how many batches
- Price materials, labour and mixer, per cum
- Compare all grades for the same volume
- Give an order list, CSV, shareable link and print
✕It does not
- Design a concrete mix or adjust for admixtures
- Correct for moisture in sand or aggregate
- Include steel, shuttering or curing
- Price ready-mix concrete, pumping or transport
- Know your local prices; change the rates to match your supplier
6FAQ
Questions
What is the mix ratio of M20 concrete?
The nominal mix for M20 is 1 : 1.5 : 3, meaning one part cement, one and a half parts sand and three parts coarse aggregate by volume. For one cubic metre of finished concrete that is about 8.1 bags of cement, 0.42 cum of sand and 0.84 cum of aggregate before wastage.
What are the mix ratios of M5, M7.5, M10, M15 and M25?
Common nominal mixes are M5 1:5:10, M7.5 1:4:8, M10 1:3:6, M15 1:2:4, M20 1:1.5:3 and M25 1:1:2. M25 and higher grades should be made from a lab design mix, so treat 1:1:2 only as a guide.
Why is the dry volume 1.54 times the wet volume?
Loose cement, sand and aggregate contain air gaps. When water is added and the mix is compacted, the gaps fill and the volume shrinks by roughly a third, so about 1.52 to 1.57 cum of dry material makes 1 cum of concrete. The calculator uses 1.54 and lets you change it.
How much sand and aggregate should go with one bag of cement?
Multiply the ratio numbers by the volume of one bag, about 0.0347 cum or 1.23 cft. For M20 that is about 1.84 cft of sand and 3.68 cft of aggregate per bag. A 35 litre gauge box holds about one bag's volume, so M20 is one bag, one and a half boxes of sand and three boxes of aggregate.
How much water is needed per bag?
Water = cement weight × water-cement ratio. At 0.5, a 50 kg bag needs 25 litres. Lower ratios give stronger, more durable concrete but need better compaction; do not add extra water on site to make it easier to pour.
What is the difference between nominal mix and design mix?
A nominal mix uses fixed volume ratios such as 1:1.5:3, measured on site. A design mix is worked out in a lab for your cement, sand and aggregate, by weight, to reach a target strength with less cement. IS 456 allows nominal mixes only up to M20.
What is a brass?
A brass is 100 cubic feet, about 2.83 cubic metres. Sand and aggregate are shown in cum, cft and brass.
Is my data stored?
No. The calculator runs in your browser and loads no third-party scripts. Inputs leave the page only if you copy the link, share on WhatsApp or download the list.
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