SVG Export - Dimensions different

I tried to find this in a previous thread and found threads discussing other dimension anomalies, but I’m trying to understand the relationship between the dimensions of lines or other objects in sketches vis a vis the dimensions of corresponding lines that show up in the exported SVG.

When I exported to SVG with the settings shown in the the attached screenshot, I got line that are approximately 133% of the original sketch’s dimensions. The 2nd & 3rd images are from Shapr and Vectornator, respectively.

It is likely the dpi settings. What program are you importing into?

Thank you for your thoughts. I have a hunch its in the DPI settings, too. Changing the DPI setting also seems to impact the weight / thickness of the strokes not sure of ratios or best practices.

The example I showed in the original post was based on import into Vectornator on the iPad. I’ve also imported into Inkscape on the Mac - same general results.

Ultimately, these sketches exports as SVGs are for the purposes creating 2D files for laser cutting a few components associated with the 3D printed components that make up the overall model.

I guess I could just continue to experiment through interpolation. But that’s time consuming and subject to error. So If anyone has a document or other explanation describing relationship between DPI setting and SVG output results, would be grateful for the insights.

I use shapr3d mostly for my 4x8 cnc plasma table. I use sheetcam and mach3. Before updating sheetcam and getting the dpi update on shapr, I had to divide shapr3d dpi (96) into sheetcams dpi of 90. (90/96= .9375) and use a 1: .9375 ratio when importing into sheetcam.

Becoming clear it’s dependent on the target application’s expectation / requirements re: DPI. Problem is it’s not intuitive and not obvious what the target app is looking for….
Through more trial / error, I was able to resolve the issue by exporting at 72 dpi.

72dpi I think is what adobe illustrator uses. I have cut files from AI by importing into sheetcam at a ratio of 1 : 1.25

I had this problem, also. When I exported SVG to my Shaper Origin digital router, it worked perfectly; the dimensions held without change. But when I wanted a to-scale pattern printed on paper, it would never be dimensioned correctly (I had tried exporting as a drawing and as an .SVG).

Solution: Super easy and obvious with existing software (and no ratios to multiply), do not know why I did not figure it out sooner. Export your sketch as an .SVG, making sure to match the DPI to your printer; in this case, my printer is a Brother MFC using 1000 DPI. Then open the SVG with your browser and FILE->PRINT from it. I used Safari, but I am sure it would work with Chrome, IE, etc.