Introduction
Steel bars are an essential component in many construction and manufacturing projects and hence its important to know how to find the weight of steel bars.
Knowing the weight of a steel bar is crucial for determining the amount of material needed for a specific project and also for calculating the load capacity.
In this article, we will discuss the steps to find the weight of a steel bar.
Normally weight is calculated from density of steel bar. Which is longer and time consuming.
Luckily, we got simplified formula for that.
Formula to find weight of steel bar
Above formula gives the weight of 1 meter length. Calculate total length of steel bar from structural drawing.
Total weight = Weight per meter X Total Length
Example Calculation
For example, let us assume we have to find the weight of 10mm dia bar.
Using the above equation,
Weight of 1m length of 10mm dia bar = 10*10/162.2 = 0.616kg
If we calculate the total length of 10mm bar from structural drawing as 500m,
Then total weight of steel required = 500*0.616 = 308kg
We may order 5% extra to this considering the wastage and lap length.
Derivation of formula
Step 1: Determine the Volume of the Steel Bar
The first step in finding the weight of a steel bar is to determine its volume.
The volume of a circular steel bar can be calculated using the following formula:
Volume = Area * Length (Area = π*d2/4 )
Step 2: Determine the Density of Steel
The density of steel is 7,850 kilograms per cubic meter (kg/m3).
This value remains constant, regardless of the size of the steel bar.
Step 3: Calculate the Weight of the Steel Bar
To find the weight of the steel bar per meter length, multiply its volume by its density.
Weight of steel
= Volume * Density of Steel
= π*d2/4 * 7850
= (3.14*d2*10-6/4) * 7850 Kg [10-6 is multiplies to convert dia in mm to meter]
= 6.16*10-3 *d2 Kg
= d2/162.2 kg
Unit weight of different dia steel bars
Unit Weight of 8 mm dia steel
= 82/162.2
= 0.395 kg
Unit Weight of 10 mm dia steel
= 102/162.2
= 0.616 kg
Unit Weight of 12 mm dia steel
= 122/162.2
= 0.89 kg
Unit Weight of 16 mm dia steel
= 162/162.2
= 1.58 kg
Unit Weight of 20 mm dia steel
= 202/162.2
= 2.46 kg
Unit Weight of 25 mm dia steel
= 252/162.2
= 3.85 kg
Unit Weight of 32 mm dia steel
= 322/162.2
= 6.31 kg
Table having weight of commonly used steel bar
Calculation would be even faster if you know the unit weight of commonly used steel bar
| Dia of Bar | Weight of Bar per meter |
| 8mm | 0.395 kg/m |
| 10mm | 0.616 kg/m |
| 12mm | 0.89 kg/m |
| 16mm | 1.58 kg/m |
| 20mm | 2.46 kg/m |
| 25mm | 3.85 kg/m |
| 32mm | 6.31 kg/m |