I have a reference line retrieved from a raster image in the background that I know in real life measures 10 mm (l_ref). I want to scale the whole picture so that everything has real dimensions.

I use the measuring instrument to get the length (l_mes) then I do in my Mac shift+cmd+m scale proportionally and apply to each object separately 100/(l_mes/l_ref) %.

enter image description here When I measure again the line has the same length, I don't understand why. Is there a better way?

  • HI! Maybe a picture showing before / after scaling could help us understand your issue.
    – Juancho
    Nov 26, 2021 at 17:11
  • @Juancho I discovered that I have to deselect the measuring tool and reselecting it. Here a gif to explain the workflow (sorry that is in italian, but the lunghezza which is lenght stay the same)
    – G M
    Nov 26, 2021 at 17:20
  • Does this answer your question? How do I resize line segments of a larger object to absolute values. Your maths doesn't work out either. It should be 10/83.27*100 to work out the percentage for scaling. After you've input it into the "width" field, you also need to hit the Apply button in the Transform dialog.
    – Billy Kerr
    Nov 26, 2021 at 18:27
  • @BillyKerr thanks for the link! yes I press on apply unfortunately the gif skip that frame. Your formula is correct, but also mine.
    – G M
    Nov 26, 2021 at 19:49

1 Answer 1


The transform-panel modifies objects by setting a 'transform'-attribute on the object's internal XML-element. The measure-tool, however, doesn't take this attribute into account when calculating the length, meaning it displays the length the object would have without the applied scale (this is probably a bug).

What you can do is, either use the width and height input in the toolbar to manipulate the size instead, group your object by itself before scaling with the transform-panel then ungrouping it again, or use the 'Apply Transform' extension.

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