I'm sure this is a user error as I am 100% a novice at Inkscape. I am looking to format SVG files at a set size. I have resized the objects inside Inkscape but when I export the SVG and then import it in the plotter software I use it is 3 times larger. 

I know I can resize it without quality loss but i am looking to streamline my design process. So i have the image to 11cm in width but it imports at 31cm. I'm certain that that there is a wy to do this but my google and youtube research has not helped me with this at all.

Can anyone explain to me like they speaking to a totally beginner? 

Please and thank you!

Please describe what plotter software you are using, and please share an example Inkscape SVG file (a 1cm x 1cm rectangle will do).

I am using Cricut Design space. I created a 1 cm c 1cm square and it imported at 2.85.

I came across this before with Cricut and if I remember the following corrected the issue:

https://maakplek.nl/wiki/doku.php?id=from_inkscape_to_fusion_without_scaling_issues&fbclid=IwAR2mOBODHCMLZefSksGKJ6MUnddARg8OJilGrpYtkiOhg7eO8Nt-SHYXSnw

I usually set my default to these values then proceed to do the designs. Not sure how to  correct existing designs.

Edit:Nope - doesn't work

The only way I was able to get it to work is:
Extensions>Document>DPI 96 to 90
 

I would set my new document properties with units=mm (or use any mm template). Then simply save the document as an Inkscape SVG and upload to DS.

Please try the attached svg. It works for me in DS.

https://maakplek.nl/wiki/doku.php?id=from_inkscape_to_fusion_without_scaling_issues&fbclid=IwAR2mOBODHCMLZefSksGKJ6MUnddARg8OJilGrpYtkiOhg7eO8Nt-SHYXSnw

Once you have done that then change the document format and display units to whatever you want. 
That works in Cricut 

You can try this (works with my Brother Plotter):

SAVE (not export) your file as "Optimised SVG". Make sure "Remove comments" is checked in the window that opens.

BookNerd

I am using Cricut Design space. I created a 1 cm c 1cm square and it imported at 2.85.

Open your testfile, select layer1, group it, save. Test in Cricut.

My guess is, you used Resize Page to Selection earlier. When you did, Inkscape applied a transform to the group element Layer 1.