Estimate parenting-time percentages from a repeating overnight schedule, or solve explicitly for percentage, parent time, or period length. These planning results do not determine legal custody or child support.

Annual nights are estimates from a repeating 14-night cycle; holidays and actual calendar dates are excluded.

Planning arithmetic only. Parenting-time percentages do not determine legal custody or child support.

Use 365 for a common year or 366 for a leap year.

Related Calculators

Custody Time Formula

The following formula can be used to calculate the child custody (parenting) time percentage for one parent over a given period.

CTP = (D / T) × 100

Variables:

  • CTP is the custody time percentage
  • D is the number of days the child spends with one parent
  • T is the total number of days in the period being considered

To calculate the custody time percentage, divide the number of days the child spends with one parent by the total number of days in the period being considered. Multiply the result by 100 to convert the fraction to a percentage.

What Is Custody Time (Parenting Time Percentage)?

In this calculator, “custody time” means the share of time a child spends with one parent during a defined period (often called parenting time or timesharing). It is typically expressed as a percentage based on the number of days (or, in many parenting plans, the number of overnights) the child is with that parent divided by the total days in the period.

How to Calculate Custody Time?

The following steps outline how to calculate the Custody Time Percentage (CTP).

  1. First, determine the number of days the child spends with one parent (D).
  2. Next, determine the total number of days in the period being considered (T).
  3. Next, use the formula from above: CTP = (D / T) * 100.
  4. Finally, calculate the Custody Time Percentage.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Number of days the child spends with one parent (D) = 20

Total number of days in the period being considered (T) = 30

Custody Time Percentage (CTP) = (20 / 30) × 100 ≈ 66.667%