The scale bar won't work on my map when I try to insert one, is there a way to define a scale manually?
Map elements—Help | ArcGIS for Desktop did you follow the help topic?
Yes, I looked at that and tried changing the display units etc. When I put a scale bar on the map it is not right, it is much too small of a distance.
I suspect you need to check your data and your data frame units before you worry about the layout view
Specifying a coordinate system—Help | ArcGIS for Desktop 0.016 miles sound like you have decimal degree data and no coordinate system defined somewhere
All my data is defined as British National Grid
Perhaps you could nudge the thread to a successful conclusion by reporting the coordinate system of the data frame, the units used and maybe even a screen grab of the legend. Strangely 0.0016 * 5260 is 8 feet which probably isn't your desired unit but 0.0016 is about 114 meters at about latitude 50. So the 0.0016 is in some unit that has reflects the units defined somewhere.
Please elaborate: "The scale bar won't work on my map"
An area which I know is miles across comes up as 0.0016 miles, so I need to define it myself in some way?
Do you have multiple data frames, and if so, is the one for your scale bar activated?
Just the one data frame
Are you sure that you've correctly defined the coordinate system for the layer you know is miles across? If not, it may appear much smaller (or larger) than you think. Does it match with other known correct layers?
As far as I know I have, but I'm guessing that the coordinate system is most likely the problem causing my scale bar not to be correct.
The scale bar and data should automatically adjust themselves to match the data frame (project on-the-fly), so as long as the data is correctly defined and the data frame is using a "reasonable" coordinate system (e.g. not azimuthal or something), the scale bar should be correct. Please try adding some known correct data if you haven't already. Otherwise, a screenshot may help.
That's a factor of a million out, possibly. 1 mile = 1600m.
Are you importing a cad file - is it in mm instead of metres? (or visa versa)
If you're then measuring in km and not miles you would get 0.0016........, if my mental arithmaguestimation is correct.
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