Enter the number of days the child spends with one parent and the total number of days in the period being considered into the calculator to determine the custody time percentage. This calculator can also evaluate any of the variables given the others are known.

Custody Time Formula

The following formula can be used to calculate the custody time percentage.

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 a Custody Time?

Custody Time refers to the period during which an individual is held in a legal custody, typically in a jail or prison, while awaiting trial or after being sentenced. This time can be considered when determining the individual’s overall sentence, potentially reducing the time they must serve post-conviction. The length of custody time can vary greatly depending on the nature of the charges, the legal process, and the jurisdiction’s laws and regulations.

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, gather 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