Steel is probably the most widely used material in construction and engineering, and for good reason. It is strong, durable and reliable. That’s why it is important to know the weight of steel in order to start a project.
The weight of steel affects material costs, transportation, handling, the structure of the design, and fabrication. To lower costs, you have to correctly calculate the weight of steel. The formula for calculating steel weight also reduces the guesswork and saves time. For professional steel fabrication, you can visit https://rapidfabricationservice.com/.
What Is The Weight Formula For Steel?
The weight formula for steel is easily memorized and is:
Steel Weight = Volume × Density
The density of carbon steel typically is around 7,850 kg/m³.
To find the volume, you will need to know the shape and size of the steel product. As an example, the volume for a steel plate is:
Volume = Length × Width × Thickness
Next, you multiply the volume by the density of steel.
For a steel plate that looks like this:
- Length: 2 meters
- Width: 1 meter
- Thickness: 10 mm
We will first convert the thickness to meters, since the formula uses meters.
10 mm = 0.01 m
Next is determining the volume which is:
2 × 1 × 0.01 = 0.02 m³
Now we multiply the volume by the density of steel:
0.02 × 7,850 = 157 kg
Thus the steel plate weighs around 157 kg.
Why Should Steel Weight Be Calculated?
Calculating weight of steel is essential for several reasons.
- One, the weight calculation will enable you to gauge the total cost of the material and will help with budgeting. Steel is always bought by weight.
- Two, the weight of steel will determine the cost of transportation. Heavy steel products require special vehicles, lifting equipment and extra handling.
- Three, designers of machinery and buildings will need to know the weight of steel for each building and machine. All the components of a structure will affect the weight of the structure.
Weight calculations are used by fabricators as well and can help reduce waste and stabilize costs of a project.
Steel Weight Calculations in Different Units
Steel dimensions can be given in various units such as millimeters, centimeters, meters, inches and feet. Answers will not be correct unless measurements are done in the same units.
For a steel plate, one easy metric formula is
Weight (kg ) = Length (m) X Width (m) X Thickness (mm) X 7.85
Suppose we have a steel plate which is
- 2 m in length
- 1 m in width
- 10 mm in thickness
Calculation is
2 X 1 X 10 X 7.85 = 157 kg
This makes it easier since we do not need to convert mm into m.
Steel Plate Weight Formula
Steel plates are used in construction of almost all buildings, bridges; machines and equipment, fabrication and manufacture of tanks and other machines.
The general formula is
Weight of Steel Plates = Length X Width X Thickness X 7,850 kg/m³
However, if any dimension in the formula is in meters then other dimensions must be in meters too.
Let’s look at a steel plate that is 3 meters long, 1.5 meters wide, and 12 mm thick.
To convert millimeters to meters, 12 mm = 0.012 m.
Now let’s calculate the volume:
3 × 1.5 × 0.012 = 0.054 m3
To calculate the weight, we need to multiply the volume by the density of steel:
0.054 × 7,850 = 423.9 kg
Therefore, we can say that this steel plate weighs approximately 424 kg.
Weight of Steel Bars
Now let’s look at the weight of steel bars.
Steel bars that have a circular cross section weigh slightly differently than bars that have a rectangular cross section.
Let’s calculate the area first.
Area = π × Diameter² ÷ 4
Once we know the area, we can multiply by the length and the density of steel.
There is also this shortcut for circular steel bars.
Weight per meter (kg/m) = Diameter² ÷ 162
Here, the diameter needs to be in millimeters.
Now let’s use a steel bar that has a diameter of 20 mm.
20² ÷ 162 = 2.47 kg/m
This means that the weight of a steel bar that is 20 mm in diameter is approximately 2.47 kg per meter.
If this bar is 6 meters long, we would estimate that the weight of this bar is 14.82 kg.
Weight of Steel Pipe
Now let’s talk about the weight of steel pipe.
The weight of steel pipe is dependent upon the outer diameter, inner diameter, wall thickness, and the length of the pipe.
Because a pipe is hollow, we can’t use the same equation that we used for the solid steel bar.
The general equation to find the cross-sectional area is:
Area = π ÷ 4 × (Outer Diameter² − Inner Diameter²)
Once we know the area, we multiply it by the length of pipe, and then by the density of steel.
Most pipe manufacturers include weight tables for standard pipes. The tables list the estimated weight per meter of different pipe sizes and wall thicknesses.
Determining the weight of pipes using the manufacturer’s table is faster and more accurate than calculating each pipe individually.
Weight of a Steel Beam
Steel beam section shapes may include:
- I-beams
- H-beams
- channels
- angles
Determining the weight of a beam, from its dimensions, is usually more complex than determining the weight of a simple plate.
For standard structural steel sections, it is often easier to use a value of weight per meter that has been published by the manufacturer.
For a steel beam that weighs 30 kg per meter and is 6 meters in length:
30 × 6 = 180 kg
The beam weighs approximately 180 kg.
It is helpful to estimate weights of standard steel sections for construction and fabrication work.
Common Steel Value Densities
The density of different grades of steel can be slightly different, but typically, for the purposes of estimating the weight of steel, 7,850 kg/m³ is used. Stainless steels and other alloy steels may have different densities, and therefore you should refer to the material specification if you need a high degree of accuracy. Although, for most cases, using the standard density is fine. However, it is recommended that you use the density for the selected material if the project is important or large. Read more about steel density and weight calculations.
There are a number of factors that can contribute to the final weight of a steel product.
Dimensions
Length, width, weight, and diameter all can affect the amount of steel used. Increasing any of these measurements will generally increase the weight.
Steel Grade
Different types of steel alloys can have different densities. The differentiation can seem minor, but can become significant when dealing with larger volume calculations.
Shape
Different steel plates, bars, pipes, beams, channels and angles have different cross sections. Different shapes have their own respective weight calculation formulas.
Quantity
The weight of one steel component may not seem significant, but the total weight of hundreds or thousands of components can be substantial.
Manufacturing Tolerances
Actual fabricated dimensions may vary +/- within the manufacturing tolerances. As a result, the actual weight may be different than anticipated.
How to Calculate Steel Weight Accurately
Simple steps to follow.
- Identify the type and shape of the steel.
- Measure the appropriate dimensions.
- Ensure all dimensions are consistent.
- Calculate the volume or cross section.
- Use the appropriate steel density.
- Multiply the volume and density.
- Compare the result to a steel weight table.
- Use CAD or engineering software.
A more detailed explanation of metal fabrication is available.
The Difference Between Theoretical and Actual Steel Weight
Let’s assume a steel plate has a calculated weight of 157 kg. With the right dimensions and shape of the steel component, it becomes somewhat easier to estimate the cost of the material, facilitate the movement of the material, calculate the loads of the structure, and prepare for the fabrication of the component. It also becomes easy to provide a quote for fabrication. It is important to note that the calculated steel weight is theoretical. The actual weight may be slightly different.
The final weight may be affected by several factors such as:
- the fabrication tolerances
- surface coatings
- cutting processes
- machining processes
- material composition
Let us consider the case of a steel plate that has a calculated weight of 157 kg. The actual weight may slightly differ from this calculated weight.
For routine planning and buying, the theoretical weight works just fine. In critical cases, you are expected to use actual weight and certified data.
Final remarks
It is quite obvious that the formula for weight of steel is the easiest to understand when you know the dimensions and the shape of the steel component.
Basic weight of steel formula is:
Weight = Volume × Density
A density of about 7,850 kg/m³ is generally used for steel.
The most important thing is to find the correct volume. The volume and density of different steel products differ and the shape and type of the product also affect this.
Calculating weight of steel accurately also helps you to estimate how much the product may cost and how much you may be expected to pay for the transportation of the product, and also to determine the loads and prepare a quote for fabrication of the product.
For complex steel components, a reliance on professional fabrication and engineering services is justified. Rapid Fabrication Service can assist with creating custom fabrication solutions dependent on various project parameters.
