Sorry, I'm not sure where to post this.

I used the support calculator xls sheet on this forum. Is the number it calculates for me per child? Sorry, I found it very confusing. Based on the KCSG spreadsheet, it's not even close to that figure?

This is correct.  The amount calculated is for all children.  Make sure that all of the parameters in step 1 are entered correctly and make sure you are referring to the new 2012 child support guidelines.  These are not in effect until April 1st, but some judges are already using them.

If the calculator is not correct, please share the details with us so we can figure out where the error is.

Increased by $1200 a year or per month? And whose income? The total or just one parent's?

Depending on the income levels, a $1200 increase in income should probably create a change in child support.  Keep in mind that Mom's income has very little to do with how much is paid (currently).  Also, depending on how much time Dad spends with the kids, a parenting time adjustment may be appropriate.