Updated July 10th, 2019

We often need to calculate steel quantity of different RCC members in a construction project before ordering for purchase. We often do this manually in the project.

We actually need to calculate steels for different RCC members when we need that. Because over-purchasing steels (MS Bar) can block a huge amount of money as it is highly priced material.

You also can’t order less quantity than the required quantity. Because it will hamper your project’s workflow.

So, at different stages of construction of a building project, we need to calculate the steel for different RCC members to know the required quantity.

In this post, we will see how to calculate the steel quantity in footings.

## What is a footing?

I think you all know about this. A footing is the most bottom part of a building. And it is a part of the substructure. There are many types of footing used for a building. It depends on the structural design of the building.

In this post, I’ll discuss how to estimate reinforcement or steel quantity of a footing

## How to Calculate Steel Quantity of a Footing

Calculating steel quantity of footing is easy. You just need to find out the length of steel bars and then convert the total length of bars into kilogram as steel is sold in **Kilograms** or **Tons **(*1 Ton=1000 kilogram*).

The process to calculate steel quantity is same for different types of footings.

Once you’ve learned to estimate steel quantity for one type of footing, you’ll be able to estimate steel quantity for any type of footings.

So, I’ll show you how to calculate steel quantity for an Isolated footing.

## What is an Isolated Footing?

An isolated footing is normally used to support a single column. It can be a square or rectangular shape.

If you know how to calculate the quantity of steel for an isolated footing, you’ll be able to calculate steels for other types of footings.

So, let’s see how to calculate steel quantity for an isolated footing.

## How to Calculate Steel for an Isolated Footings

You’ll need structural drawing sheets of footings for calculating steel.

Things you’ll require for estimating steel quantity of footings –

- Size of footings
- Reinforcement details of footings

In structural drawings, you will find all the details required to calculate steel and it is somehow shown in the drawing as shown in the image below.

From the above image, the size of the footing is **4′ x 6′ x 1′**

And,

The reinforcement details are,

**16**mm∅ bar@**4″**c/c along the long side, and**20**mm∅ bar@**4″**c/c along the short side.

That means you’ll need to place **16mm** dia bar at **4″** center-to-center (c/c) distance along the long side and **20mm** dia bar at **4″** center-to-center (c/c) distance along the short side of the footing.

*So, let’s calculate the steel quantity for the footing.*

To calculate the steel quantity, we first need to calculate the required number of bars for both directions. Then we need to find the length of one bar. If you multiply the number of required bars with the length of one bar then you will find the total length of bars. Once you found the total length of bars, you need to convert that length into **kilograms** or **Tons**.

So, let’s see how we can calculate the steel quantity for our example footing.

### A formula for Calculating The Number of Bars

To find out the required number of bars for a footing, use the following formula,

**Number of bars = {(length or width of footing – concrete cover for both sides) ÷ spacing} +1**

For our example footing,

*Number of bars along the short side of the footing,*

= {(6′ – 3″ x 2) ÷ 4″} + 1 [*Concrete clear cover for footing is 3″*]

= {(6′ – 6″) ÷ 4″} + 1

= (5½′ ÷ 4″) +1

= 17.67

*Say*, **18 Nos**.

*Number of bars along the long side of the footing,*

= {(4′- 3″ x 2) ÷ 4″}+1

= {3½′ ÷4″} + 1

= 11.61

*Say*, **12 Nos**.

### A formula for calculating the length of a steel bar

To find out the length of a steel bar use the following formula.

**Length of a bar = length or width of footing – concrete cover for both sides + 2 x length of a bend**

For our example footing,

*Length of a steel bar along the width of the footing,*

= 4′ – 2 x 3″ + 2 x 6″

= **4½ feet**.

*Length of a steel bar along the long side of the footing is,*

= 6′ – 2 x 3″ + 2 x 6″

= **6½ feet**.

### Finding total length of bars in the footing

*The total length of bars along the short side of the footing is,*

= number of bars x length of a bar

= 18 x 4½′

= **81 feet** (*20mmØ bar*).

*The total length of bars along the long side of the footing is,*

= number of bars x length of a bar

= 12 x 6½′

= **78 feet** (*16mmØ bar*).

If the same size of bars is used in both directions then you can sum up both quantity of the bars. But, in our example footing, we used different size of bars. So, we will calculate the steel quantity for different diameter bars separately. For purchasing the steel, we need to convert the required length of steel into kilogram.

From the above calculation, we found –

Required **16mmØ** bar for our example footing is,

= 81 feet

**= 38.88 kilograms**

And, Required **20mmØ** bar is,

= 78 feet

**= 58.50 kilograms**

* Read More:* How to convert steel quantity from feet to kilograms.

In our example footing, we use a **single reinforcing net**. But, in your building project, you may find some footings with the **double reinforcing net**. In that case, you need to follow the same procedure again to calculate the steel quantity for another reinforcing net too.

So far, we calculated the quantity of steel for a footing. Now let’s see how we can calculate footing’s steel quantity for a building project.

## How to Calculate The Steel Quantity in Footing for a Building Project

A building has many footings with different sizes and shapes. You’ll need to calculate the steel quantity for those footings too.

For making the steel calculating process easy for footings of a building construction project,

- first, summarise the similar type of footings
- Secondly, calculate the steel quantity for each type of footing separately and
- Finally, multiply the calculated steel quantity by the number of each type of footings.

*For example*, you have **10** numbers of footing for **F1** type and **5** numbers of footings for **F2** type and so on.

For calculating the steel quantity for **F1** type footing, you just need to calculate the required steel quantity for one footing of that type and then multiply that quantity by **10**.

*Similarly*, for **F2** type footing, calculate the steel quantity for one number of footing than multiply that quantity by **5**. And so on.

After calculating steel quantity for the footings of the building project, add the steel quantity for short columns before purchasing. Because you will need the short columns’ steel for completing the footings’ reinforcement works.

**Conclusion**

Calculating steel quantity for footings is easy. You just need to get the total required length of the steel bars of different sizes and then convert that length into *Kilograms* or *Tons* before purchasing.

**Say Something**

*How do you calculate the quantity of steel in footings for a building construction project? Please share your technique that you think easier in the comments below…*

Shafkat says

Excellent!!….Thanks, It is very simple and helpful.

Liton Biswas says

You are welcome, Shafkat.

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