Get In Touch

Get Answer To Your Queries

Select a valid category

Enter a valid sub category


Please check this box to proceed further

How To Calculate The Water Cement Ratio ?

When you are into construction, you have to be extra careful about the raw materials & their proper proportions you use. They should be of high quality and you must have knowledge about them. In the case of the concrete mix, it is always ideal to have the contractor have a proper look at it. This is because the right water cement ratio is vital for a strong & durable construction.. This is why it is necessary to understand the importance of cement water ratio and how to calculate the same.


What is water cement ratio ?

It is the ratio of the mass of water to the mass of cement added to concrete. The water cement ratio formula directly affects the strength & durability of the concrete. The typical water-cement ratio varies between 0.40 - 0.60 for different grades of concrete mix.

Water Cement Ratio in Concrete

Importance of water cement ratio :

The most important thing that determines the strength of the concrete mix is the water cement ratio.

The water cement ratio is the ultimate factor for the strength and durability of the concrete when it is cured properly. For instance, if the water cement ratio is 0.40, it means for every 50 Kg of cement(1 Bag) used in the concrete, 20 Liters of water is to be added.

How To Calculate Water Cement Ratio ?


Water cement ratio = Weight of water

                                                 Weight of cement

For example if the water-cement ratio is 0.50 for concrete and cement added is 50 kg (weight of 1 bag of cement).

Water required for concrete will be:

Water / cement = 0.50

Water / 50kg = 0.50

Water = 0.50 x 50 = 25 liters.

Similarly for W/C = 0.40

Water = 0.40 x 50

Water = 20 litres

As you see, the water is reduced as we decrease the water-cement ratio. It is a fact that when water is reduced in concrete, the compressive strength of the concrete increases. But there is some limit to the water cement ratio. The minimum water cement ratio is 0.30 - 0.35, beyond this the concrete becomes too stiff and impractical to handle.

 How to test the water cement ratio ?

Here’s how you can test the water cement ratio in concrete to ensure you have the best cement for house construction :


A simple and practical way of controlling the water content is by means of a slump test carried out by a contractor, explained below.


To conduct this test a Slump Cone of steel: 30cm high, 20cm diameter at the base, 10cm diameter on the top and provided with handles is used. Concrete is filled in the cone in layers of 7.5cm at a time, each layer being tamped 25 times with a metallic tamping rod 16mm in diameter and 60cm long. Just after the slump cone has thus been filled then it is lifted. The extent to which the concrete drops is called the slump. It is measured from the top of the cone to the top of the concrete after the cone has been removed.


The usual values of the slump of concrete used for various purposes are given below and depend upon the method of compaction possible in each case. Where there is no obstruction by way of reinforcement etc., in the movement of concrete or where the concrete can be rammed hard in the case the smaller value of slump is required.


Mass concrete and road work : 2.5 to 5 cm


Ordinary beams and slabs : 5 to 10 cm


Columns, thin vertical sections


and retaining walls etc. : 7.5 to 12.5 cm


Also Read : Concrete and it's types.



1. How does the water cement ratio affect strength ?


The lower the water to cement ratio, the fewer air pores and the more compact the concrete structure, which translates into higher strength. The high amount of water will reduce the compressive strength of the concrete because it will increase the gap between the cement.


2. What are the advantages of a low water cement ratio ?


There is reduced drying shrinkage and cracking if the water cement ratio is low. There is lower permeability and it creates a better bond between concrete and reinforcement.


3. How can we reduce the water cement ratio in concrete ?


To reduce the amount of cement you must first reduce the amount of water. Use an admixture, optimize the combined aggregate grading, add fly ash, or obtain aggregate that has a better particle shape.

 Related Articles

Recommended Videos

  Tools for Home Building

Cost Calculator

Every home-builder wants to build their dream home but do so without going over-budget. By using the Cost Calculator, you’ll get a better idea of where and how much you might end up spending.



EMI Calculator

Taking a home-loan is one of the best ways to finance home-building but home-builders often ask how much EMI they’ll need to pay. With the EMI Calculator, you can get an estimate that will help you better plan your budget.


Product Predictor

For a home builder, it is important to find the right store where one can get all the valuable information about home building. Use the Store Locator feature and visit our store for more information on home building.


Store Locator

It is important for a home builder to select the right products during the initial stages of constructing a home. Use the Product Predictor to see which products will be needed while building your home.