There is a formula to calculate the **unit weight of steel bars**. I’ll come to that point later.

**Why do we need to know the unit weight of steel bars?**

When we estimate the steel bars of a Reinforced Concrete member we actually get the length of those bars.

For example, *1000 feet 20mmø bar* or *500 feet 16mmø bar*, etc (ø – *a symbol of diameter*).

But steel bar suppliers measure the steel bars as weight. So we have to order them in weight for purchasing. The weight of steel bars can be expressed in **kilogram** or **quintal** or **ton**. [*1 quintal = 100 kg, **1 ton = 1000 kg]*

Now come to the point.

## How to Calculate The Weight of Steel Bars

We often use a formula for Calculating the weight of Steel Bars.

The formula converts the **length** of steel bars to **weight**. We can also use the formula to know the **unit weight of steel bars** of different sizes.

The Formula is, **D²L/162**

*Where,*

**D** = Diameter of steel bar in millimeter

**L** = Length of steel bars in meter

### Understanding the Formula

We know, the weight of any material is,

**=Cross-sectional area of the material × Length of the material × Density of the material**

For steel bar, this is also the same.

**The weight of steel bars (W)=** Cross-sectional area of steel bar (A) × Length of steel bar (L) × Density of steel bar (ρ).

That means,

**W = A x L x ρ**

Where,

**A** = Area = πD²/4

*π (pai) = 3.14*

**D**= Diameter of steel bar in milimeter (steel bar size is measured in millimeter).

**L**= Length of steel bar in meter

**ρ**(Rho) = Density of steel bar =**7850**kg/m³Therefore,

W = 3.14 x D²/4 x L x 7850

But there are two conflicting units in the formula. Those are millimeter for **D** and meter for **ρ** (Rho).

We have to convert either **D** from millimeter to meter or **ρ** from meter to millimeter.

Let’s convert D from **millimeter** to **meter**.

**1** millimeter = **1/1000** meter

Let’s implement this to the formula,

W= 3.14 x D²/(4x1000x1000) x L x 7850

= **D²L/162**

Using this formula we can calculate the weight of steel bars.

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### Calculating Weight of Steel Bars Per Meter

Keep in mind that the unit of **D** (*diameter of the bar*) should be in **millimeter** and **L **(*Length of the bar*) should be in **meter** in this formula.

Let’s see some examples.

__Example-1:__

**How to calculate the weight of 100 meters long 16mmø bar?**

In this example,

D= **16** millimeter

L = **100** meter

So,

W = **D²L/162**

= 16² x 100/162

= **158 kilogram** (approx)

**Answer**: Weight of the **100** meters long **16mmø** bar is **158** kilogram.

__Example-2__

**How to calculate the weight of 100 meters long 20mmø bar?**

In this example,

D = **20** millimeter

L = **100** meter

So,

W = **D²L/162**

= 20² x 100/162

= **247** kilogram (approx)

**Answer**: Weight of the 100 meters long 20mmø bar is **247** kilogram.

### Unit Weight of Steel Bar When Length is in Meter

If you put **1-meter** length for each diameter of steel bars in the formula then you’ll get the **unit weight**.

Let’s see.

W = **D²L/162**

Unit weight of,

**10**mmø bar = 10² x 1/162 =**0.617**kg/m**12**mmø bar = 12² x 1/162 =**0.888**kg/m**16**mmø bar = 16² x 1/162 =**1.580**kg/m**20**mmø bar = 20² x 1/162 =**2.469**kg/m**25**mmø bar = 25² x 1/162 =**3.858**kg/m

If you multiply the length of estimated bars with this unit weight you’ll get the total weight of steel bars for your reinforced concrete member.

For example, total weight of **1000** meter long 25mmø steel bar is,

1000 x 3.858 = **3858** kilogram.

So far we have seen the **unit weight** for each diameter of steel bar in meter basis. That means the weight of a bar per **meter**.

But what if you estimate the steel bar length in the **foot**. **What will be the formula to calculate the steel bar’s weight if the length of the bar is on the foot?**

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### Calculating Weight of Steel Bars When Length is in Foot

Again,

Weight = A x L x ρ

= 3.14 x D²/(4 x 304.80 x 304.80) x 222

= *D²L/533*

Where,

*D = Diameter of bar in mm (1 foot = 304.80 mm)*

*ρ (Rho) = 7850 kg/m³ = 222 kg/ft³ (actually it is 222.287 kg/ft³)*

Keep in mind that you always should use D as millimeter and L as feet in this formula.

### Unit Weight of Steel Bar When The Length is in Foot

If you calculate a 1-foot length of any diameter of steel bar you will get the following result and that will be the unit weight of steel bars per foot length.

Unit weight of,

- 10mm ø bar = 10² x 1/533 = 0.188 kg/ft
- 12mm ø bar = 12² x 1/533 = 0.270 kg/ft
- 16mm ø bar = 16² x 1/533 = 0.480 kg/ft
- 20mm ø bar = 20² x 1/533 = 0.750 kg/ft
- 25mm ø bar = 25² x 1/533 = 1.172 kg/ft

If you multiply the estimated length of steel bars with these unit weights you’ll get the total weight of steel bars.

For example,

Weight of 1000 feet long 10mm ø bar is,

1000 x 0.188 = 188 kg.

*Your Turn:*

*If you have any query about this post then ask me in the comments below. I’ll reply as early as possible.*

There is a formula to calculate the unit weight of steel bars. Let’s see how we can use the formula to get the weight of different sizes of bars.

Khanan says

In the above 1st example, the Dia of bar is not converted to metre, so a little bit confuse

Farida says

The conversion has been taken care of in the formular

shamin says

tks viya many many tks

Zahid says

Nicely explained –

What if the Dia of Bar is taken as desi Sutars ( LocalMarket Terms)!!

SASI KUMAR says

THANK YOU

Liton Biswas says

You are welcome, SASI.

Golam Mostafa says

The formula of calculation unit wt. of steel bar easily described thanks.

Liton Biswas says

Thanks for appreciating, Golam.

Mudassir Nazir says

Thank you

¤ very nice method using formula and calculation of the steel bars.mncp

Mohd wasim says

Thanks dada it is use fully furmola

indra.kumar says

Ok.thanks.bhai

tewodros yilma says

got u tnx

Liton Biswas says

You are welcome, Tewodros

mohammad yunus says

thanks to share the information

Liton Biswas says

You are welcome, Yunus.

akia samuel akia says

it has been so helpful

Mohd Afzal says

Very nice method

Liton Biswas says

Thank you, Afzal.

Hazwan says

Can you please explain to me how did you get the value 162.

I did try : 7850 x π / (4x1000x1000) = 6.165 x 10^-3.

Did I do something wrong here?

Thank you in advance.

Jyotiranjan Kundu says

here we first set the numerator to one(1).

So, ( 4*1000*1000)/(3.14*7850)=162

your method set the denominator to one(1)

So (3.14*7850)/(4*1000*1000)= 6.165 x 10^-3.

Ali says

Thank You

Liton Biswas says

You are welcome, Ali.

ABBAS ANSARI says

CIVIL ENGINEERING IS NOT DIFFICULT COURSE.

Liton Biswas says

Right, ABBAS.

emmanuel says

very useful . . . many thanks

Liton Biswas says

You are welcome, Emmanuel.

Eric Momolu says

I am grateful to you for this professional education I have acquired today. Your few minutes/hours explanation is equivalent to a semester lecture.

Liton Biswas says

Thank you, Eric.

balvinder says

Thanx sir

Liton Biswas says

You are welcome, Balvinder.

Niño Faith Calamba says

Hello sir! I would like to ask if the formula stated above is applicable for any grade of deformed bars?

Liton Biswas says

Yes, Niño.

Haribabu says

Thank.. U… Sir, for clearly explanation..

Liton Biswas says

You are welcome, Haribabu.

Ashok kumar pal says

how i can define pane bar formula of 1mtrs

Jyotiranjan Kundu says

Sir,

I want to know the formula of Density of steel bar.

7850 kg/cubic meter.

Dharmendra pal says

sir it’s a very important formula

Karma Zangmo says

explanation was made in such a simple way. Much appreciated.

Liton Biswas says

Glad you loved.

has says

what is the formula for RHS steel?

teddy says

Weight of 1000 feet long 10mm ø bar is,

1000 x 0.188 = 188 kg. pls convrtu feet to meter

James Tamba says

Your explanation is very clear. Thank you for helping us in this direction.

Liton Biswas says

You’re welcome, James.