# Unit Weight of Steel Bar: Steel Bar Weight, Formula

The unit weight of steel bars is the weight per unit length of a given size of steel bar. The unit weight of steel bars is typically expressed in kilograms per meter (kg/m) or pounds per foot (lb/ft).

The exact unit weight of a steel bar depends on its size, cross-sectional shape, and grade of steel used. For example, the unit weight of a 10mm diameter round bar made of Fe 415 grade steel would be different from the unit weight of a 10mm diameter square bar made of the same grade of steel.

To calculate the unit weight of a steel bar, you can use the following formula:

Unit weight (kg/m) = (mass of the bar) / (length of the bar)

where the mass of the bar can be calculated using its density and cross-sectional area. The density of steel is typically around 7,800 kg/m3.

The density of steel is around 7850 kg/m3 or 7.85 g/cm3 or 490 lbs/ft3 or 13231 lbs/yd3.

The steel weight is generally measured in Kg, Ton, and pounds.

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## Unit Weight Of Steel Bars

The standard unit weight of steel bars used in construction is given below,

## Different Diameters of Steel Bars Used In Construction

There are various steel diameters used in construction 8mm, 10 mm, 12 mm, 16 mm, 20 mm, 25 mm, 32 mm, and 40 mm. The steel diameter used for normal residential, commercial, and office building construction is 8 mm to 20 mm.

The steel diameter of 25 mm to 40 mm is used for heavy construction like bridges, dams, and retaining walls.

## The Formula Used To Calculate the Weight of Steel

The formula used to calculate the unit weight of steel bars is DÂ²/162. Where, D = Dia. Of steel bars, 162 is a constant value.

### Derivation of D2/162 Formula

Consider a steel bar with a diameter of D and a length is L.

Weight of Steel Bar (W) = Unit Weight of Steel Bar (Î³)  x Volume (V)

W = Î³ x V

W =  Ï€DÂ²/4 x Î³  (V = Ï€DÂ²/4)

Is known that Steel unit weight is about 7850 kg/m3 (Î³)

W =  Ï€DÂ²/4 x 7850

Here, D is steel diameter in mm, and the density of steel is in kg/m3. To make a constant value in the same unit we will convert Dia. Of steel in mm to m.

DÂ² mm / 1000Â²

W =  Ï€/4 x DÂ²/1000Â² x 7850

W = DÂ²/162.28 kg/m

W = DÂ²/162 kg/m

## How to Calculate Unit Weight of Steel Bars

The unit weight of the steel bar is calculated by dividing the weight of the steel bar by its volume. For calculating the unit weight of steel bars consider the unit length of 1 meter for all steel diameter steel.

### 1. Unit Weight of 8 mm steel bar

Dia of Steel = 8 mm, Length of Steel bar = 1 m

Unit weight of 8 mm steel bar

= DÂ²/162

= 8Â² /162

= 8×8/162

=64/162

= 0.395 kg/mÂ³

The unit weight of 8 mm dia. steel bar is 0.395 kg/mÂ³

8mm steel weight per meter is 0.395 kg

8mm steel bar unit weight in feet = 0.12 kg/ft

For example,

8mm steel rod weight 40 ft

= 0.12×40

= 4.8 kg

So, an 8mm steel rod weight of 40 ft is 4.8 kg

### 2. Unit Weight of 10 mm Dia. Steel Bar (10mm steel bar weight)

The following is the method to calculate the 10mm steel bar weight

Dia of Steel = 10 mm, Length of Steel bar = 1 m

Unit weight of 10 mm steel bar

= DÂ²/162

= 10Â² /162

= 10×10/162

= 100/162

= 0.617 kg/mÂ³

The unit weight of 8 mm dia. The steel bar is 0.617 kg/mÂ³.

10mm steel weight per meter is 0.617 kg

So, a 10mm steel bar weight is 0.617 kg/mÂ³.

### 3. Unit Weight of 12 mm Dia. Steel Bar

Dia of Steel = 12 mm, Length of Steel bar = 1 m

Unit weight of 12 mm steel bar

= DÂ²/162

= 12Â² /162

= 12×12/162

= 144/162

= 0.890 kg/mÂ³

The unit weight of 8 mm dia. The steel bar is 0.890 kg/mÂ³.

12mm steel weight per meter is 0.890 kg

### 4. Unit Weight of 16 mm Dia. Steel Bar

Dia of Steel = 16 mm, Length of Steel bar = 1 m

Unit weight of 16 mm steel bar

= DÂ²/162

= 16Â² /162

= 16×16/162

= 256/162

= 1.58 kg/mÂ³

The unit weight of 8 mm dia. The steel bar is 1.58 kg/mÂ³.

16mm steel weight per meter is 1.58 kg

### 5. Unit Weight of 20 mm Dia. Steel Bar

Dia of Steel = 20 mm, Length of Steel bar = 1 m

Unit weight of 20 mm steel bar

= DÂ²/162

= 20Â² /162

= 20×20/162

=400/162

= 2.46 kg/mÂ³

The unit weight of 20 mm dia. The steel bar is 2.46 kg/mÂ³.

20mm steel weight per meter is 2.46 kg

### 6. Unit Weight of 25 mm Dia. Steel Bar

Dia of Steel = 25 mm, Length of Steel bar = 1 m

Unit weight of 8 mm steel bar

= DÂ²/162

= 25Â² /162

= 25×25/162

=625/162

= 3.85 kg/mÂ³

The unit weight of 25 mm dia. The steel bar is 3.85 kg/mÂ³.

25mm steel weight per meter is 3.85 kg

### 7. Unit Weight of 32 mm Dia. Steel Bar

Dia of Steel = 32 mm, Length of Steel bar = 1 m

Unit weight of 32 mm steel bar

= DÂ²/162

= 32Â² /162

= 32×32/162

=1024/162

= 6.32 kg/mÂ³

The unit weight of 32 mm dia. The steel bar is 6.32 kg/mÂ³.

32mm steel weight per meter is 6.32 kg

### 8. Unit Weight of 40 mm Dia. Steel Bar

Dia of Steel = 40 mm, Length of Steel bar = 1 m

Unit weight of 40 mm steel bar

= DÂ²/162

= 40Â² /162

= 40×40/162

= 1600/162

= 9.87 kg/mÂ³

The unit weight of 8 mm dia. The steel bar is 9.87 kg/mÂ³

40mm steel weight per meter is 9.87 kg

## How to Calculate the Weight of Steel Bars on a Construction Site

The following are the steps to be followed to find out the quantity of steel available on the construction site or if steel was loaded in the truck at the time of delivery.

Step: 1 Recognize the Different Diameters of Steel Available in Stock

Firstly, we have to recognize the different dia. Steel bars are available on-site.

Suppose, there are 8 mm, 10 mm, 16 mm, and 20 mm steel bars available on site.

Step: 2 Count the Number of Steel Bars of Each dia. Of Steel

Now, count the number of steel bars in each dia. Steel bars are available on-site.

For example,

8 mm = 80 nos.

10 mm = 120 nos.

12 mm = 50 nos.

16 mm = 60 nos.

20 mm = 30 nos.

Step: 3 Find out the Unit Weight of Steel Bars

Now calculate the unit weight of steel bars by taking a 1 m length sample of each dia of steel and weighing it.

This weight of 1 m length sample will directly give you the unit weight of that steel bar dia in kg/m.

The unit weight of steel bars is as follows,

8 mm = 0.395 kg/m

10 mm = 0.620 kg/m

12 mm = 0.89 kg/m

16 mm = 1.58 kg/m

20 mm = 2.46 kg/m

Step: 4 Calculate the Total Weight of Each dia Steel Bars

From unit weight and numbers of steel bars, calculate the total weight of each dia steel bar available on site.

For Example,

1. 8 mm Dia steel Nos = 80, Unit Weight of 8 mm Dia Steel = 0.395 kg/m

Total Weight of 8 mm dia steel = Nos x Unit Wt x Length of Steel (12 m)

= 80 x 0.395 x 12

= 379.2 kg

2. 10 mm Dia steel Nos = 120, Unit Weight of 10 mm Dia Steel = 0.620 kg/m

Total Weight of 8 mm dia steel = Nos x Unit Wt x Length of Steel (12 m)

= 80×0.620×12

= 892.8 kg

3. 12 mm Dia steel Nos = 50, Unit Weight of 12 mm Dia Steel = 0.890 kg/m

Total Weight of 12 mm dia steel = Nos x Unit Wt x Length of Steel (12 m)

= 80×0.89×12

= 534 kg

4. 16 mm Dia steel Nos = 60, Unit Weight of 16 mm Dia Steel = 1.58 kg/m

Total Weight of 8 mm dia steel = Nos x Unit Wt x Length of Steel (12 m)

= 80×1.58×12

= 1137.6 kg

5. 20 mm Dia steel Nos = 30, Unit Weight of 20 mm Dia Steel = 2.46 kg/m

Total Weight of 20 mm dia steel = Nos x Unit Wt x Length of Steel (12 m)

= 80×2.46×12

= 885.2 kg

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