How can I scale something with actual measurements in meter,cm,etc? What a want to do is a big cylinder which is going to have a diameter of .285 m and do several cut loops but when I want to do an scale and type the units of that cut loop (for example 0.335 m) in meters it gives me an smaller circle instead of a bigger one and that's incorrect due to the units of the original cylinder.
As mentioned, Scale is unitless, it's just a multiplier for the actual Dimensions. 

The only solution is to divide the Final Dimension by the Current Dimension (FD/CD). You can type that directly into the scale value, Blender calculates it for you. So in your case type .335 / .285 which will result in a Scale of 1,17544 and your loop will have the correct dimension.