Internal/External Feature Size Is Off

[mendells 52]

I have been having this issue for a long time now and have adjusted my models to make everything work but its been bugging me recently so I thought I would post and see if others have been having the same issue.

When I print a part the internal and external features of the part are about 0.12mm (.005") too small regardless of the feature size. So If I print a 10mm box and a part with a 10mm square hole both features will come out about 9.88mm. The same thing happens with a 20mm, 50mm or even a 100mm part, they all come out small. I have tried this with all four of our UM2+ printers and multiple materials all with similar results. I could understand if the exterior features were small and the internal features were big (under extrusion or incorrect line width) or if the internal feature was off less than the external feature (material shrink after cooling) but I cannot for the life of me figure out how a 20mm box with a 10mm square hole could be 0.12mm too small on both features?

Anyone else experience this problem?