The width of the cut binding has a direct relation to the width of the seam. A good guide to start with is cut the binding 6 x the width of the seam allowance (this is for a double fold binding) No this doesn't always work depending on the depth of the batting.
Also, the width of the binding also depends on if you have to maintain a 1/4" for seams on the quilt top. If no outside seams then the binding can be wider. But it a choise and how the finished product will look.
As an example I use 3/8" seam allowances and cut the binding 2 1/4 or 2 1/2" depending on the batting.
The binding should be full and seam even and consistent. Suggest you start with a 1.5" and try a short section and see if this will give you the look you want. If too tight then make the cut binding a bit larger.