Nominal IS Code Concrete Mix Ratio Calculator Metric

This nominal concrete mix ratio calculator can help you design simple concrete mixtures in seconds. The method is based on the IS code for nominal concrete mixtures, and on the commonly used practices.

We designed this calculator to be as simple as possible, in which users only needs to fill few fields to get their results.

It is important to know the limits and the applicability of this method when compared to more advanced methods. For more details about the nominal mix concrete mix ratio method based on the IS code, read the following article, “Concrete Mix Proportioning (Ratio & Design)“.

At the very beginning, we provided two tables to summarize the main concept behind this calculator. The first table shows the mix ratios, by weight, for M5 to M20, based on the IS 456-2000.  Whereas, the second table shows the concrete mix ratios, by volume, for M5 to M25, based on the commonly used proportions. 

Step 1: Choose the grade of concrete

The first step is to select the grade of concrete, either M5, M7.5, M10, M15, M20, or M25. In fact, the letter ‘M’ stands for ‘Mix’, and the following number stands for the compressive strength at 28 days.

Step 2: Specify your required volume

The next step is to enter the volume, in cubic meters. To make it even easier, we provided another tool which helps you easily determine the volume of concrete for your project. You can check it out here.

Step 3: Enter the proportion of fine aggregate to coarse aggregate by mass

In this field, you should enter the proportion of fine aggregate to coarse aggregate. Generally, this proportion is 1:2, however it is subjected to an upper limit and a lower limit according to IS 456-2000 Table 9. This step is only needed for method 1 in the results section, which will explain later.

Step 4: Enter the specific gravity and bulk density for each material

In this step, you should enter the specific gravity and bulk density of the materials. If you do not know the exact values, the tool provides you with predefined values which are within the typical ranges.

Step 5: Check the results

In this nominal concrete mix ratio calculator, the results section is divided into three sub-sections. In fact, each sub-section represents a different method of calculations. Mainly, they provide you with the weight of each material in kg per the volume you entered previously, and the dry volume of each material.

• First Method: Based on the IS 456-2000, with calculations following the absolute volume method.
• Second Method: Based on the commonly used nominal mix ratios, with calculations following the absolute volume method.
• Third Method: Based on the commonly used nominal mix ratios, but with calculations following the “1.54” conversion factor.

Furthermore, we provided two notes at the end to show the assumed parameters, and the adjustments that should be made in case you are using materials of different conditions.

The first method takes into account the various factors and weight ranges addressed in the IS 456-2000. In addition, the user can adjust the proportion of fine aggregate to coarse aggregate within the limits as per the aforementioned standard. Hence, this method is somewhat flexible and provides accurate results which meet the IS 456.

The second method is similar to the first, but is based on slightly different set of data. Basically, comparing the two tables provided at the beginning of this concrete mix ratio calculator, we can see that the ratios are actually close, taking into account the conversion to either weight or volume ratios. Hence, the results between method 1 and method 2 are usually close, depending on the input. However, this method does not consider any adjustments to the proportion of fine to coarse aggregate. One advantage of this method over the previous one is that the user can determine approximate proportions for M25 concrete, whereas the maximum in the previous method is M20.

The third method follows the same set of data as the second method, however it is based on the “1.54” conversion factor from wet to dry concrete, and not on the absolute volume method. This method usually gives higher actual volume than required. This may be beneficial considering the main aim of nominal mix ratios, which simplify the proportioning of concrete for simple works without the need of advanced calculations. Thus, a slightly higher volume can cover waste in materials, approximations in some input values, and other factors.

We will illustrate the mix proportions for m5, m7.5, m10, m15, m20, and m25. For simplicity, we will consider a volume of 1 cubic meters, a fine to coarse aggregate proportion of 1:2, and use the predefined values for specific gravity and bulk density of cement, sand, and gravel.

Solution

First, we will specify the grade of concrete in the first field. Second, in the required volume field, we will insert the value “1”, since the considered volume is 1 cubic meters. Third, we will leave the fine to coarse aggregate proportion as 1:2. And fourth, we will keep the specific gravity and bulk density of cement, sand, and gravel as the predefined values. The following figure shows an example of the data input for an m5 mix.

Next, we will discuss the results based on the three methods, for each mix separately. This concrete mix ratio calculator shows the results in two ways for the given volume. The first is the proportions by weight in kg, which is straight forward. And the second is the proportions by dry volume. We will thoroughly explain how to use this data in a practical way on site later.

M5 concrete mix ratio

An m5 concrete mix ratio based on method 1 of this concrete mix calculator with the given input is (1 : 5.33 : 10.66 : 1.2) by weight. And, based on methods 2 and 3, the mix ratio is (1 : 5 : 10 : 1.73) by volume.

This m5 concrete mix ratio results in an output for the three methods, summarized in the following table.

M7.5 concrete mix ratio

The m7.5 concrete mix ratio based on method 1 is (1 : 4.16 : 8.33 : 0.9) by weight, for the given input. And, for methods 2 and 3, the mix ratio is (1 : 4 : 8 : 1.29) by dry volume.

The proportions for this m7.5 concrete mix ratio for the three methods are shown in the following table.

M10 concrete mix ratio

The m10 concrete mix ratio based on method 1 is (1 : 3.2 : 6.4 : 0.68) by weight, for the given input. And (1 : 3 : 6 : 0.98) by dry volume for methods 2 and 3.

The proportions of the constituent materials for this m10 concrete mix ratio are illustrated in the following table.

M15 concrete mix ratio

The m15 concrete mix ratio based on method 1 is (1 : 2.2 : 4.4 : 0.64) by weight, for the given input. And, for methods 2 and 3, the mix ratio is (1 : 2 : 4 : 0.92) by dry volume.

The proportions of cement, sand, gravel, and water for this m15 concrete mix ratio are shown in the following table.

M20 concrete mix ratio

The m20 concrete mix ratio based on method 1 is (1 : 1.66 : 3.33 : 0.6) by weight, for the given input. And, for methods 2 and 3, the mix ratio is (1 : 1.5 : 3 : 0.86) by dry volume.

The proportions of the materials for this m20 concrete mix ratio are illustrated in the following table.

M25 concrete mix ratio

The m25 concrete mix ratio based on methods 2 and 3, is (1 : 1 : 2 : 0.8) by dry volume, for the given input. For method 1, the followed code does not cover the ratios for m25 as a nominal mix.

The proportions for this m25 concrete mix ratio are shown in the following table.

Discussion on the results

As seen in the above tables, methods 1 and 2 give very comparable results, with just a slight difference. Whereas, method 3 gives higher quantities, since as previously mentioned, it gives a higher total volume than the required.

The results by weight are obviously straight forward, and easy to implement on site with proper tools and equipment.

However, this is not always the case with nominal mix ratios, which are often used when more advanced methods are not applicable for any reason, and in minor construction works that do not require precise mix designing. Thereby, we will discuss a way to use the proportions by weight and by dry volume easily on site even when the required measuring and weighing tools and equipment are not available. 

Hence, we will simply present the previous data in a different way, taking into account both the weight and dry volume of constituents.

Example

Let us consider the basic tools that are commonly available on site with standard sizes (bags of cement, a wheelbarrow, and a bucket) to proportion the previous mixtures, and determine some measurements. The given measurement data is as follows:

• Weight per cement bag = 50 kg.
• Volume of bucket = 20 L.
• Capacity of wheelbarrow = 65 L.

Determine how many bags of cement, wheelbarrows of sand and gravel, and buckets of water are required for previous mixtures based on method 2.

Solution

For the m25 concrete mix ratio, based on method 2, one cubic meter of concrete requires 9.48 bags of cement (474/50 = 9.48), 5.06 wheelbarrows of sand (0.329/0.065 = 5.06), 10.12 wheelbarrows of gravel (0.658/0.065 = 10.12), and 13.15 buckets of water (308/20 = 3.15). 

For the rest of the mixtures, the same calculation method is applicable. In brief, the following table shows the results for the different concrete mixes based on method 2.

This concrete calculator helps in designing mixes according to the nominal mix by IS 456-2000.