System Information
Operating system: Linux Mint 19.1
Graphics card: GeForce GTX 960 (GPU 0)

Blender Version
Broken: 2.80
Worked: 2.79b

Short description of error
At the moment of export I need to set the "Scale" value to 1000.0 in order to get the proportions properly.

Exact steps for others to reproduce the error
Based on the default startup or an attached .blend file (as simple as possible).

1. Create a .blend file with a mesh with correct measurements.
2. Select File > Export > Stl (.stl)
3. Export normally and try to see the model on another application that uses .stl files, like Repetier Host