Use (click) the Accounting function in the HP Printer Utility. It will list all your recent jobs (even jobs you have deleted) and details. Click Export to Excel. You can then use Excel to total ink and/or paper usage and multiply by any cost per unit you choose to use.
I was using a online HP profit caculator for my prints. But since they changed his site , there is no more caculator... the link is broken.
I use differents kind of papers, and some cost more, some cost less. So, since there is no more caculator how can I do that myself? maybe better question is... how you know the cost of each thing you print in the z3100?