Check that your printer driver is printing actual size and not scaled or scaled to fit the page.

thanks Andy, I checked all that and also opened the pdf and dxf with coreldraw. the dimensions were off in corel as well. I exported after saving in mil and mm with no difference. not sure what's going on. It used to work fine for me on earlier versions of easyeda. As a workaround after I export the pdf from easyeda then print the pdf at 80% it will scale it down to the dimensions in my easyeda file. if anyone out there has time and is running the latest version of easyeda V6.4.31 it would be great if you could export a PCB outline and see if everything looks okay

@mjeth, I created a board outline of 100mm x 100mm then exported it as a PDF with the PCB **View** set to **100%**. Then I printed it onto an A4 sheet with the printer driver **Scale** set to **100%** and **Page** Scaling set to **None**. The board outline on the paper measures exactly 100mm x 100m.

thanks for checking! at least I know it's on my end now