How to calculate metal weight

Calculate steel weight

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If you need or want to determine the weight of a steel part, you can either weigh it or you have to calculate the steel weight.

Especially with larger parts, the possibility of weighing them is usually ruled out in the private sector.

When calculating the weight of steel and other metals, there are various options that are more or less suitable depending on the size and type of object.

In any case, you need the specific weight of the metal or steel type if you cannot or do not want to use an online calculator. A distinction is usually made between flat steel, square tube, square steel, round steel, steel tube and sheet steel.

Steel weights

Depending on the alloy, the specific weight is different for different types of steel. However, the differences are not so great that they play a significant role in most everyday applications.

If you want to know exactly, you have to take the specific weight from a steel table. Here is a brief overview of the specific gravity of stainless steel and unalloyed steel, but there are numerous alloys and types.

  • View round steel on Amazon »

Steel weight table

A cube with an edge length of 10 cm (cubic decimeter) has the following weight

with unalloyed steel7.85 kg
with stainless steel V2A7.90 kg
with stainless steel V4A8.00 kg

Round bars - calculate weight

To calculate the weight of round steel, we need the formula for the volume of a cylinder. This is V =? · R² · h.

Example calculation: The round steel whose weight we want to calculate is 10 mm in diameter and one meter long.

  • Converted into the formula 3.14 x (0.5 cm x 0.5 cm) x 100 cm = 78.5 cubic centimeters.
  • Since a cubic decimeter is 1000 cubic centimeters, that is the result
  • 0.0785 cubic decimeter x 7.85 kg specific weight of mild steel = 0.616 kilograms.

Calculate tube weight (formula for cylinder volume)

Formula and shape do not differ from round steel, only two cylinders have to be calculated here. Once based on the outside diameter and once from the inside diameter.

In the end, only the volume of the inner cylindrical cavity has to be subtracted from the volume of the cylinder with the outer diameter. The volume remains for the pipe.

Example: The weight of a steel pipe with an outside diameter of 5 cm and a material thickness of 5 mm and a length of one meter should be calculated.

Insert the dimensions in the volume formula (V =? R2 h) and calculate:

  • Volume based on the outer diameter: 3.14 x (2.5 cm x 2.5 cm) x 100 cm = 1962.5 cubic centimeters
  • minus the volume of the cavity: 3.14 x (2 cm x 2 cm) x 100 cm = 1256 cubic centimeters
  • Result: 706.5 cubic centimeters. These 706.5 cubic centimeters are 0.7065 cubic decimeters x 7.85 kg specific weight = 5.546 kg is the weight of the pipe.

The approach with a rectangular tube is the same as with a round one, only that the volume formula of a cuboid must be used here, i.e. length x width x height.

Calculate sheet steel weight as well as flat and shaped steel weight (formula cuboid volume)

The formula for determining the cuboid volume is used for all shapes that are basically rectangular:

Length x width x height or often also called a x b x c.

In the case of structural steel, i.e. profile girders, several are calculated, otherwise the calculation corresponds to that of flat steel or sheet steel.

Example calculation: A flat piece of V4A steel is one meter long, 10 cm wide and 1 cm thick. So the calculation is:

  • 1 cm x 10 cm x 100 cm = 1000 cubic centimeters, which is exactly 1 cubic decimeter.
  • A cubic decimeter of V4A steel has a specific weight of 8 kg / cubic decimeter
  • the flat steel therefore weighs 8 kilograms

Danger: With the mere assessment without a mathematical approximation or concrete weighing, you will quickly be wrong. Would you have thought that a sheet of steel that is 1 x 1 m and 5 mm thick weighs almost 40 kilograms?

Calculate small parts made of steel

In the case of complex shapes (figures, etc.), the volume can be determined by measuring the amount of liquid that they displace, provided they are not sensitive to short-term moisture.

Place the part in a container and fill it up until the part is covered. Mark the waterline.

Remove the part and fill it up with a measuring cup until the container is filled up to the mark made. The part has as much water as had to be refilled.

One liter corresponds to one cubic decimeter. For example, if you had to refill 2 liters, that would be 2 x 7.85 kg, i.e. 15.6 kilograms, for unalloyed steel.

Calculate steel weight online

There are weight calculators for metal from various steel manufacturers. There you only have to specify the type (i.e. sheet metal, flat steel, pipe, etc.) as well as the dimensions (diameter, length, width, etc.) and, if necessary, the alloy in order to calculate simple and common steel parts.

Steel Excel spreadsheets and similar tools can also be found online for the same purpose.

When looking for a tool, simply specify what you would like to calculate. For example, »Calculate V2A steel pipe«.

Photo credits: Pixabay, detaildesign, Pixabay, imonedesign, Pixabay, PublicDomainPictures, Pixabay / DilanIDStudio, Pixabay / JAHuddelston (sorted chronologically or according to the order of the images used in the buying guide)


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