Personally I find the "Hailey Calculator" a lot better, even if it does make my tort slightly under weight.
My Spur Thigh has always been well over weight using the JR Graph (the one you can print).
I've never understood the "JR Calculator Ratio method"
http://www.tinytortoises.co.uk/healthy%20growth.html
used by the OP, it seems to work at the lower end of the graph but it is doesn't with larger torts at the other end. (compared to the original graph)
I'll stick with Hailey from now on.
