I am looking to purchase a length of steel tubing with the following dimensions 1800mm x 25mm x 25mm with a wall thickness of 3mm. How much weight will be able to support at mid point if supported at both ends? I am looking to use it for a long desk.

Thanks in advance

  • Before some amount of sag or before total collapse? You might be surprised how floppy steel tubing is. I don't consider it useful for that type of situation. Angle iron would be better, with a flange of 50mm or more.
    – isherwood
    Jul 18, 2018 at 11:28

1 Answer 1


The tubing that you suggested 1800mm x 25mm x 25mm with wall thickness of 3mm can be converted to an approximate dimension of 72" long, 1"x1" square outside size and a wall thickness of 0.118". The deflection calculator at this site suggests that such tubing supported at the very ends would experience a deflection of almost a half an inch with a 100 pound load applied right at the center of its length.

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I would not consider this piece of tubing to be at all suitable for supporting a table or desk that was 1800mm from end to end and only supported at the ends. You would be far better off to use rectangular tubing that was 25mm x 50mm with the 50mm deployed in the vertical direction. You could also consider the use of 50mm x 50mm square tubing with a wall thickness of 5mm and achieve much better results.

  • Ok thank you very much for this information, i'm going to look at sourcing some of this today
    – Jake Rote
    Jul 19, 2018 at 9:10

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