If Poser had a tape measure tool, like the one in Max, this would be simple to determin.  But it doesn't, and neither does Daz Studio.  So all you'd need to do is go in Daz Studio, load the native figure, Genesis, then pose it with arms to the sides.  Export her to Max, with proper scale conversion to whatever units you are modelling your cane, and size it accordingly.

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Tools :  3dsmax 2015, Daz Studio 4.6, PoserPro 2012, Blender v2.74

System: Pentium QuadCore i7, under Win 8, GeForce GTX 780 / 2GB GPU.