In Wisconsin, child support is calculated using guidelines published in Chapter DWD 40 of the Wisconsin Administrative Code.  

Wisconsin Child Support Program Website 

In general, the guidelines require a person paying child support to pay a percentage of his/her gross income.  17% for 1 child, 25% for 2 children, 29% for 3 children, 31% for 4 children, and 34% for 5 or more children.

Links

Forms