Concrete Mix Ratio: Grade Table, Nominal vs Design Mix and How to Calculate
November 3, 2026
Key Takeaways
- A concrete mix ratio is the proportion of cement, sand, and stone, such as 1:1.5:3 for M20.
- M20 is the highest grade for which nominal mix concrete is permitted under IS 456, subject to the applicable code provisions.
- M25 and above have no fixed ratio; they need a design mix.
- Site ratios are by volume, but IS 456 prefers batching by mass.
- Water is not part of the ratio. IS 456 Table 9 sets it per 50 kg bag of cement, from 30 litres for M20 up to 60 litres for M5.
What Is a Concrete Mix Ratio?
A concrete mix ratio is the proportion of cement, fine aggregate (sand), and coarse aggregate (crushed stone) in a concrete mix, written in that order. So 1:1.5:3 means one part cement, one and a half parts sand, and three parts stone. Mix ratio and mix proportion are the same thing, and the final strength is expressed as a grade such as M20.
Water is not one of the three numbers. It is controlled separately through the water-cement ratio, which is why two mixes with the same ratio can have very different strengths.
| Material | Role in the mix | Typical Indian source | Standard |
|---|---|---|---|
| Cement | Binder that hardens and gives strength | OPC 43/53, PPC | IS 269 / IS 1489 |
| Fine aggregate | Fills voids between stones; improves cohesion | River sand or manufactured sand (M-sand), 4.75 mm and below | IS 383:2016 |
| Coarse aggregate | Forms the load-bearing skeleton | Crushed stone, typically 10–20 mm | IS 383:2016 |
| Water | Reacts with cement and makes the mix workable | Potable water | IS 456 |
Disclaimer: This information is for general reference only. Actual concrete mix proportions must comply with applicable IS codes and project requirements. Structural concrete must follow the approved mix design or other method permitted by the applicable code and approved by the responsible engineer.
One common confusion: cement and sand alone, with no stone, is mortar, not concrete. Mortar ratios such as 1:4 or 1:6 are used for brickwork and plaster and do not describe concrete grades.
Commonly Referenced Concrete Mix Ratios (M5 to M20)
IS 456 specifies nominal mixes by mass. The table below shows those figures alongside the volume ratios used on site.
| Grade | Total aggregate per 50 kg bag (kg) | Water per 50 kg bag (L) | Water-cement ratio | Site shorthand (cement : sand : stone, by volume) |
|---|---|---|---|---|
| M5 | 800 | 60 | 1.20 | 1:5:10 |
| M7.5 | 625 | 45 | 0.90 | 1:4:8 |
| M10 | 480 | 34 | 0.68 | 1:3:6 |
| M15 | 330 | 32 | 0.64 | 1:2:4 |
| M20 | 250 | 30 | 0.60 | 1:1.5:3 |
IS 456 Table 9 prints the aggregate and water quantities per 50 kg of cement, by mass. Ratios such as 1:2:4 are site shorthand for those quantities; the code itself does not print them.
Fine to coarse aggregate is generally 1:2 by mass, within a range of 1:1.5 to 1:2.5.
Nominal Mix vs Design Mix: Which Grades Have a Fixed Ratio?
IS 456 permits nominal mix concrete up to M20, subject to the applicable provisions. Table 9 specifies limits for aggregate quantities and water content per 50 kg of cement, along with guidance on aggregate proportions. Design mix concrete is preferred, and a nominal mix needs the permission of the engineer-in-charge (IS 456 Cl. 9.1.1). Grades above M20 require a design mix.
| Point | Nominal mix | Design mix |
|---|---|---|
| Basis | Proportions based on IS 456 Table 9, subject to its specified limits | Proportions calculated for a target mean strength (IS 10262:2019) |
| Measured by | Usually volume on site | Mass (weigh-batching) |
| Grades permitted | M20 and below | Any grade; mandatory above M20 |
| Strength assurance | General, based on the table | Based on tested materials and trial mixes |
| Cement economy | Often richer than needed | Optimised for the materials used |
| Who sets it | Table 9 | Mix designer / RMC plant laboratory |
| Typical use | Small PCC and low-grade RCC | Structural RCC, high-rise, special exposure |
How are mixes proportioned? Three methods
The arbitrary method is simply the nominal ratio, such as 1:2:4. Fineness modulus is a sand-grading index, not a proportioning method on its own. In India, structural mixes are proportioned by design mix under IS 10262:2019.
Is there a standard mix?
No. IS 456 recognises two ways of proportioning concrete: nominal mix (Cl. 9.3) and design mix (Cl. 9.2). “Standard” is not a third method with its own ratio. In IS 456 it describes a group of grades starting at M25 (Table 2). Grades above M20 need a design mix, which is why M25 has no fixed ratio.
Water in the Mix
Water is not part of the cement:sand:stone ratio, but IS 456 Table 9 limits it for nominal mixes. Per 50 kg bag of cement, the limit runs from 30 litres for M20 (water-cement ratio 0.60) up to 60 litres for M5.
If more water is needed for placing and compaction, the cement content must be increased in proportion so the water-cement ratio is not exceeded (IS 456 Cl. 9.3.1). Adding water alone weakens the concrete.
Is Concrete Mix Ratio by Volume or by Weight?
Concrete materials should generally be measured by mass for better accuracy. IS 456 permits volume batching where weigh-batching is not practicable, subject to the applicable code provisions and approval. Ready-mix plants generally use weigh-batching systems.
How to batch by volume correctly
- Use a gauge box to measure sand and coarse aggregate consistently when volume batching concrete. The box size should suit the batching method being followed.
- Use the same box for sand and stone, scaled to the ratio, for example, 1.5 boxes of sand for 1:1.5:3.
- Allow for bulking: damp sand can occupy more volume than dry sand due to bulking. This can affect volume batching, so check the sand condition and adjust the quantity before mixing.
- Add water in measured amounts, correcting for moisture already in the aggregates.
| Method | Accuracy | Where used |
|---|---|---|
| Volume (gauge box) | Approximate; affected by bulking and loose density | Small sites |
| Mass (hand-weighed) | Better; consistent | Where scales are available |
| Plant weigh-batching | Controlled batching using weighing equipment and suitable quality checks | Ready-mix plants |
Note: Batching accuracy depends on the equipment, materials and applicable requirements. Use suitable measurement and quality-control procedures for consistent concrete production
How to Calculate Cement, Sand and Aggregate from a Mix Ratio?
To find the materials for 1 m³ of finished concrete, add the ratio parts, then multiply by 1.54. This factor allows for the dry volume of materials being greater than the finished concrete volume.
Worked example, 1:2:4 (M15 shorthand):
- Sum of ratio parts: 1 + 2 + 4 = 7
- Dry volume needed: 1.54 m³
- Cement volume: 1.54 × 1 ÷ 7 = 0.22 m³. At 1,440 kg/m³ that is about 317 kg, or 6.3 bags of 50 kg.
- Sand: 1.54 × 2 ÷ 7 = 0.44 m³
- Stone: 1.54 × 4 ÷ 7 = 0.88 m³
| Grade | Shorthand | Cement per m³ | Sand (m³) | Stone (m³) |
|---|---|---|---|---|
| M5 | 1:5:10 | 139 kg (2.8 bags) | 0.48 | 0.96 |
| M7.5 | 1:4:8 | 171 kg (3.4 bags) | 0.47 | 0.95 |
| M10 | 1:3:6 | 222 kg (4.4 bags) | 0.46 | 0.92 |
| M15 | 1:2:4 | 317 kg (6.3 bags) | 0.44 | 0.88 |
| M20 | 1:1.5:3 | 403 kg (8.1 bags) | 0.42 | 0.84 |
Add site wastage on top, and confirm quantities before placing a material order.
What Decides the Right Mix Ratio?
The structural engineer’s specification decides the grade; the factors below decide whether a given proportion will actually deliver it.
Key Factors That Decide Your Mix Ratio
| Factor | What it affects | The simple rule |
|---|---|---|
| Strength | Required concrete grade and mix proportions | Follow the grade and mix design specified by the engineer. |
| Steel reinforcement | Concrete grade and durability requirements | Follow the applicable code and approved structural drawings. |
| Weather | Setting, curing, and moisture conditions | Follow the specified concreting and curing procedures. |
| Workability | Ease of placing and compacting concrete | Do not add extra water without technical approval. |
| Sand and stone | Workability, strength, and mix proportions | Use aggregates that meet the required specifications. |
| Cement type | Strength development and setting behavior | Follow the approved mix design for the cement being used. |
Golden Rule: If a general code table and your engineer’s drawing disagree, the engineer’s drawing always wins.
Note: These are standard benchmarks. Always check your actual site materials (sand/stone) and follow your engineer’s final plan.
Typical Mix Ratios by Structural Element
| Element | Grade guidance | Practical note |
|---|---|---|
| PCC below footing | Typically M7.5 to M10 | Used as a levelling or base layer |
| RCC footing / foundation | M20 minimum in mild exposure, M25 in moderate (IS 456 Table 5) | Depends on structural and exposure requirements |
| Column / pillar | M20 minimum in mild exposure, M25 in moderate (IS 456 Table 5) | Follow approved drawings and mix design |
| Beam / lintel / plinth beam | M20 minimum in mild exposure, M25 in moderate (IS 456 Table 5) | Follow approved drawings and mix design |
| Slab / roof | M20 minimum in mild exposure, M25 in moderate (IS 456 Table 5) | Follow approved drawings and mix design |
| Ground-floor PCC base | Typically M7.5 to M10 | Depends on the intended application |
The structural engineer’s drawing governs.
Five Common Mix-Ratio Mistakes
| What you will often read | What is correct | Basis |
|---|---|---|
| M25 is 1:1:2 | There is no code ratio above M20; M25 needs a design mix | IS 456 cl. 9.3, Table 9 |
| 1:2:3 is the standard mix | 1:2:3 is not an IS 456 reference proportion. In India, 1:2:4 and 1:1.5:3 are site shorthand for the M15 and M20 proportions in Table 9. | IS 456 Table 9 (the code prints mass and water, not volume ratios) |
| Design mix is mandatory from M20 | Nominal mix is permitted up to and including M20 | IS 456 cl. 9.3 |
| Add water until it flows | Excess water can reduce concrete strength and durability. Always follow the approved mix design. | IS 456 cl. 9.3.1 |
| A richer mix is always safer | Cement above 450 kg/m³ (excluding fly ash and GGBS) should not be used without special design consideration, because it raises heat and shrinkage cracking. Strength also depends on the water-cement ratio, compaction and curing. | IS 456 cl. 8.2.4.2 |
A sixth, frequent mix-up: cement-and-sand ratios (1:4, 1:6) are mortar, not concrete.
Note: These points are general reference benchmarks based on standard IS 456 clauses.
How Ready-Mix Concrete Is Proportioned?
Ready-mix concrete is bought by grade (like M25 or M30), not by a fixed ratio.
The factory calculates the exact amount of ingredients needed using laboratory tests. The ingredients are proportioned by mass, with suitable batching controls and adjustments for aggregate moisture. The mix proportions are determined through mix design and material testing. Ready-mix concrete is generally ordered by grade and specified performance requirements rather than by a nominal ratio such as 1:2:4.
What to specify when ordering:
- Grade (for example M25 or M30)
- Exposure condition
- Slump (workability) at the point of placing
- Maximum aggregate size
- Placing method (pump, crane, direct discharge)
Aparna RMC offers ready-mix concrete for different project requirements. Contact Aparna RMC to confirm available grades and request a price quote.
Frequently Asked Questions On Concrete Mix Ratio
What is the standard concrete mix ratio in India?
There is no single concrete mix ratio for every project in India. M20 is the minimum grade for reinforced concrete in mild exposure, and M25 in moderate exposure (IS 456 Table 5). The nominal shorthand for M20 is 1:1.5:3, and for M15 it is 1:2:4; these are site shorthand for the Table 9 proportions. Concrete above M20 requires a design mix. Always follow the approved project specifications.
Does the concrete mix ratio include water?
No. The three numbers represent cement, sand, and coarse aggregate. Water is controlled separately based on the specified water-cement ratio, workability requirements, and applicable code provisions. For nominal mixes, IS 456 Table 9 limits water to 30 litres per 50 kg bag of cement for M20, and up to 60 litres for M5.
Is 1:2:4 stronger than 1:3:6?
Yes. 1:2:4 contains more cement per cubic metre than 1:3:6. 1:2:4 is site shorthand for the M15 proportions in IS 456 Table 9, and 1:3:6 is shorthand for M10.
Does using OPC 53, OPC 43 or PPC change the concrete mix ratio?
The nominal proportions may remain the same, but cement type can affect strength development and other concrete properties. For design mix concrete, the proportions should be determined based on the cement and other materials used, the required strength and the project conditions.
Can I use M-sand in a nominal mix?
Yes, if it meets IS 383. Its grading zone affects the sand-to-stone balance, so check the zone and silt content.
Can a nominal mix be used for RCC?
Nominal mix concrete is permitted up to M20 under IS 456, subject to the applicable provisions and approval requirements. Design mix concrete is preferred. The required grade and mix must follow the project’s structural specifications.
Why not just use a richer mix to be safe?
Using more cement does not automatically make concrete safer or stronger. Excessive cement content can increase heat generation and shrinkage. Concrete strength also depends on the water-cement ratio, material properties, compaction and curing. Follow the approved mix design.
How much cement is in a 1:1.5:3 mix per cubic metre?
Roughly 8 bags (about 400 kg) using the 1.54 dry-volume rule. See the M20 page for the full breakdown.
What is target mean strength?
It is the average strength a design mix must be proportioned to achieve, so that the concrete still meets its grade after normal variation. IS 456 and IS 10262:2019 define it as the characteristic strength plus a margin based on the standard deviation. See the concrete grades guide for the full method.
What is a 1:2:3 mix?
It is not an IS 456 reference proportion. In India, the nominal shorthand ratios are 1:2:4 for M15 and 1:1.5:3 for M20.
Can sea water be used to mix concrete?
No. IS 456 (Cl. 5.4.3) says sea water shall not be used for mixing or curing concrete because of its harmful salts. The only exception is plain concrete with no embedded steel, and only in unavoidable circumstances after the disadvantages and precautions have been considered. Never use sea water for reinforced concrete, because the salts corrode the steel.
Disclaimer: This information is for general reference only. Actual mix proportions and material quantities may vary. Always follow applicable IS codes, approved mix designs and the structural engineer’s recommendations.