Updated March 8th, 2019

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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How to calculate materials for different-ratio concrete

### 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?**

**You May Want to Read:**

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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

03/08/2017 at 5:39 amIn the above 1st example, the Dia of bar is not converted to metre, so a little bit confuse

Farida says

27/12/2017 at 2:09 pmThe conversion has been taken care of in the formular

Chetan Kumar Singh says

21/05/2019 at 4:55 pmWeight of steel =D^2 L/162 then sir what is the 162

Liton Biswas says

22/05/2019 at 9:31 amHi Chetan,

Thank you for enquiry. I’ve discussed the thing in the post. Please read the post attentively.

shamin says

30/09/2017 at 3:12 pmtks viya many many tks

Zahid says

06/10/2017 at 10:24 pmNicely explained –

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

SASI KUMAR says

06/11/2017 at 4:46 pmTHANK YOU

Liton Biswas says

08/11/2017 at 8:35 amYou are welcome, SASI.

Golam Mostafa says

14/11/2017 at 12:35 pmThe formula of calculation unit wt. of steel bar easily described thanks.

Liton Biswas says

14/11/2017 at 7:59 pmThanks for appreciating, Golam.

Mudassir Nazir says

15/11/2017 at 4:40 pmThank you

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

Mohd wasim says

18/11/2017 at 9:28 pmThanks dada it is use fully furmola

indra.kumar says

27/11/2017 at 2:01 pmOk.thanks.bhai

tewodros yilma says

10/12/2017 at 6:11 pmgot u tnx

Liton Biswas says

11/12/2017 at 8:27 pmYou are welcome, Tewodros

mohammad yunus says

28/12/2017 at 10:14 pmthanks to share the information

Liton Biswas says

29/12/2017 at 11:14 amYou are welcome, Yunus.

akia samuel akia says

08/01/2018 at 8:26 pmit has been so helpful

Mohd Afzal says

18/01/2018 at 11:32 pmVery nice method

Liton Biswas says

20/01/2018 at 8:53 amThank you, Afzal.

Hazwan says

24/01/2018 at 2:01 pmCan 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

30/03/2018 at 6:38 pmhere 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

31/01/2018 at 2:52 pmThank You

Liton Biswas says

31/01/2018 at 7:25 pmYou are welcome, Ali.

ABBAS ANSARI says

05/02/2018 at 12:56 pmCIVIL ENGINEERING IS NOT DIFFICULT COURSE.

Liton Biswas says

06/02/2018 at 8:59 amRight, ABBAS.

emmanuel says

23/02/2018 at 12:05 amvery useful . . . many thanks

Liton Biswas says

23/02/2018 at 6:05 pmYou are welcome, Emmanuel.

Eric Momolu says

23/02/2018 at 9:05 pmI 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

24/02/2018 at 8:12 amThank you, Eric.

balvinder says

27/02/2018 at 10:03 amThanx sir

Liton Biswas says

28/02/2018 at 9:04 amYou are welcome, Balvinder.

Niño Faith Calamba says

03/03/2018 at 12:50 pmHello sir! I would like to ask if the formula stated above is applicable for any grade of deformed bars?

Liton Biswas says

04/03/2018 at 8:26 amYes, Niño.

Haribabu says

07/03/2018 at 12:38 pmThank.. U… Sir, for clearly explanation..

Liton Biswas says

10/03/2018 at 9:01 amYou are welcome, Haribabu.

Ashok kumar pal says

07/03/2018 at 6:15 pmhow i can define pane bar formula of 1mtrs

Jyotiranjan Kundu says

30/03/2018 at 6:42 pmSir,

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

7850 kg/cubic meter.

Dharmendra pal says

23/04/2018 at 11:30 amsir it’s a very important formula

Karma Zangmo says

22/06/2018 at 11:16 amexplanation was made in such a simple way. Much appreciated.

Liton Biswas says

12/07/2018 at 9:03 pmGlad you loved.

has says

11/07/2018 at 9:35 amwhat is the formula for RHS steel?

teddy says

07/10/2018 at 3:57 pmWeight of 1000 feet long 10mm ø bar is,

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

James Tamba says

01/11/2018 at 9:42 pmYour explanation is very clear. Thank you for helping us in this direction.

Liton Biswas says

03/11/2018 at 7:45 amYou’re welcome, James.

sweta says

14/12/2018 at 11:18 amThanks for the positive way to explain.

I am really glad to visit again

Keep it up!

Liton Biswas says

14/12/2018 at 11:23 amYou’re welcome, Sweta.

Champions Premium says

10/01/2019 at 1:26 pmEffective and Essential post for me. Thanks for the valuable information.

Dipayan Roy Basunia says

22/04/2019 at 6:26 pmThank you

Liton Biswas says

23/04/2019 at 8:05 amYou’re welcome, Dipayan.

Professor LatifZ says

30/04/2019 at 1:02 amA real, remarkable feat of tutorials / discussions rarely seen or heard ; originated by Civil Engineer!

Keep doing good refined work of educating professional weaklings – Stay blessed Mr. Liton Biswas 👍

Looking forward

Latif Z

Liton Biswas says

30/04/2019 at 7:48 amI’m glad, Professor. Thank you for commenting.