When you have kids, part of divorce is creating a custody agreement between the parents. After creating a custody schedule, the courts calculate child support based on parent income and the amount of time the child spends with each parent. Two main methods are used to calculate parent time percentages. The method you use depends on where you live since each state differs.

Parent time affects the child support calculations determined as part of the divorce process. The idea is that when the child spends time with a parent, the parent is providing financial support during that period of the child's life, even if he is the non-custodial parent. If a child spends very little time with one parent, that person should pay the other parent more child support because he isn't covering the day-to-day expenses. Conversely, if a child spends a significant amount of time with the parent, he likely covers a large portion of his expenses, so he should owe less in child support. Accurate parent time percentages help the courts generate fair child support calculations.

One method of calculating child custody percentages is by using the number of overnight visits each parent has with the child. To get the percentage, add up the total number of nights your child spends with you during the year. Divide that number by 365 to get your percentage. If your child spends two nights with you every other weekend and one night during the week at your home, that equals 104 nights per year. Divide 104 by 365 total days in the year for a custody percentage of 28.5 percent.

The number of overnights your child has at your house may be a little more complicated to calculate. You might have more time with your child during the summer, for example. Holidays often alternate from year to year. In states using the overnight calculation, you don't get credit for a partial day if your child doesn't spend the night. If your child spends a few hours at your house every Wednesday evening but doesn't spend the night, that day doesn't count toward your child custody percentage.

The other method of calculating child custody percentage takes a little more work because you have to calculate the number of hours your child spends with you in a year. This method is beneficial if your child spends time with you during the day without actually spending the night. Those hours that your child spends with you count toward your percentage.

It may take a little more work to figure out the number of hours your child spends with you. If the schedule is relatively the same every week or every other week, start by calculating the number of hours spent during that time period. Add in any extra time, such as holidays or summer time. If your child is with you every other weekend from 5 p.m. on Friday until 7 p.m. Sunday, that equals 50 hours every weekend she's with you. Since there are 52 weeks in a year, you would have 50 hours of parenting time for 26 weeks per year for a total of 1,300 hours a year, assuming you don't have any extra time with your child. Divide 1,300 by 8,760 hours, which is the amount of time in a year, for a total of 14.8 percent.