I am trying to calculate the road density in my study landscape. I am using the spatial analyst, and the line density function. By default, the tool is setting a cell size of 3.6km*3.6km, and the window to 30819. The results look correct visually (high density of roads show up as such), but the values dont make sense. The range is from 0-.23, which I am interpreting as .23 km per 12.96km2. These values are very very low, and are definitely not correct. Am I making a very big oversight? The projection is in WGS_1984_World_Mercator, and the study site is in India.
EDIT : The default output of line density is in kilometer per square kilometer. So the output of the tool is already what you are looking for (you don't need to divide it again by the size of the circle, this is done automatically).
Note that the vector-based approach from @Anggik will be more precise, however you will not have overlapping window analysis.