There isn't a specific formula for calculating alimony in North Carolina, and the calculator above should be considered a rough estimate. NC Child Support Calculator, covering primary, joint, and split custody.Calculate monthly support with the North Carolina guidelines. Use this worksheet when one parent (or a third party) has primary physical custody of all of the children for whom support is being determined. The amount of child support you pay or receive for children of your relationship. The NC child support calculator is another resource intended to help parents determine how much money they will pay in monthly child support. The calculation is primarily based on the gross income (pre-tax income) of the parties involved. North Carolina does not have a calculator to determine spousal support like they have for child support. Results vary from county to county, and judge to judge. This calculation is based on North Carolina Child Support Guidelines and will calculate child support based on a primary, shared or split custody arrangement.