GIMP editor, how to set selection and trim image for production?

Question

Using GIMP editor for Microsoft Windows. I have scanned an image and need to prepare the file for printing and the print file size/dimensions should be 88.5 x 57 mm: How can I set a rectangular selection to these dimensions and trim the image?

Answer 1

1. Convert your physical size to pixels using your target resolution.

2. In the options of the Rectangle Select tool, check Fixed select Size and enter the result from the previous step:

   

3. Click on the actual document to position your selection as desired.

4. Image → Crop to Selection.

If you do not have your target resolution, you can fix the aspect ratio in step 2 instead.