# How to Calculate the Weight of a Steel Bar? – With Example Calculation

Do you think it’s that simple formula (D2 / 162.2) for steel weight calculation of a bar?

Nope…

It’s hard to find the exact weight of steel bars according to its area, it is advisable to refer the manufacturer’s chart to calculate the weight of the steel bar.

If you can’t find the details, then the below steel bar weight calculation formulas are useful for site level execution.

First of all, there is no one correct steel weight calculation method or formula, just make use of this as an example.

# Steel Bar Weight Calculation

## By Calculation method

These are some examples of site level calculation which are not accurate but best to judge the approximate.

### For MS Flat Bar

For 1-meter length of Mild Steel bar of size 40 mm width and 20 mm breadth, Weight  = Volume X Density

= width (mm) X Thickness (mm)  X 7.85 Kg/mm3

= (40 X 20) X 0.00785 (converted the 7850 kg/m3 to 0.00785 g/mm3)

= 6.28 Kgs/ metre

### For Circular Rebars (most used formula at site level) Here is the formula,

Formula for Unit weight of steel = D2/162.28  Kg/m

Let’s take an example,

If we want to calculate the unit weight of 8mm steel rod of 2-metre height,

Weight of steel = 82/162.28

= 0.3944 kg/m * 2m

= 0.79 kg

So 1- meter of 8 mm steel weighs around 0.79kg.

### What is D2/162.2 in this calculation?

Here is the derivation of that D2/162.2,

Weight of steel bar per meter = Area of the steel x Density of steel x Bar length

= (3.14 x D2 /4)  x  7850 kg/m x 1m (refer these posts basic formulas  & unit weight of materials)

= (Dx 6162.25)/(1000 x 1000)

= D2 X (0.006162)

= D2 X 1/(0.006162)-1

= D2/162.28

## Experiment method,

Weight of any material (Mass) = Volume X Density

If we are calculating the weight for standard steel bar as shown in the picture, then it hard to calculate the area because of the ridges.

It can be done by Archimedes theory, We hope you have learned this in school level.

• Take a sample length of a steel bar (Ex. 1 meter)
• Take the same length of Capped PVC pipe at one side (diameter should be more than enough to insert the rod)
• Fill the PVC pipe with water up to the top
• Immerse the rod into PVC pipe gradually. (According to Archimedes theory)
• Now remove the rod from the pipe and start to fill the pipe with water using some measuring device
• Now we know the volume of water filled in the pipe is the volume of our sample rod.

Now we can calculate the exact weight of a steel rebar using the above simple formula