This calculator divides each parent’s overnight count by the total overnights to show the percentage of parenting time each parent has, based on a custody schedule.
Custody Time Calculator
Each parent's share of a child custody/parenting-time schedule, from the number of overnights with each parent.
What the Custody Time Calculator Covers
This calculator covers custody time percentages, parenting time splits, and overnight-based custody calculations — a common way courts, mediators, and co-parents measure how a custody or parenting-time schedule divides time between two households.
This is not legal advice. Custody determinations depend on many factors beyond a simple overnight count, and family courts in different jurisdictions may calculate or weigh parenting time differently. Use this calculator as a general reference, and consult a family law attorney for guidance specific to your situation.
How Parenting Time Percentage Is Calculated
Formula
Parent A Percentage = Parent A Overnights ÷ (Parent A Overnights + Parent B Overnights) × 100
Parent B Percentage = Parent B Overnights ÷ (Parent A Overnights + Parent B Overnights) × 100
Where:
- Parent A/B Overnights = the number of overnights each parent has with the child over a given period (commonly a year, or one full custody cycle)
Worked Example
Over a 14-day custody cycle, Parent A has 9 overnights and Parent B has 5 overnights.
Parent A Percentage = 9 ÷ (9 + 5) × 100 = 9 ÷ 14 × 100 ≈ 64.3%
Parent B Percentage = 5 ÷ 14 × 100 ≈ 35.7%
Under this schedule, Parent A has just under two-thirds of the overnights, and Parent B has just over one-third.
Why Overnights Are the Common Metric
Many custody calculations, including some child-support formulas, use overnight counts rather than daytime hours because overnights are easier to document consistently across a long custody schedule. Still, some jurisdictions and specific court orders may use a different measurement method.
Frequently Asked Questions
Does this percentage determine child support automatically?
No — while many child support formulas do factor in a parenting-time percentage, the actual calculation involves additional variables set by state guidelines. This calculator only produces the parenting-time percentage itself, not a support amount.
What counts as an overnight?
Generally, an overnight is counted for whichever parent the child is with at bedtime or at a specified cutoff time, though the exact definition can be set by a custody order or local court rule — confirm the applicable definition if precision matters for your case.
How do I calculate this over a full year instead of one cycle?
Multiply your custody cycle’s overnight counts by the number of cycles in a year, or simply total your actual overnights from a full year’s calendar and enter those totals directly.
Can this calculator handle three or more caregivers?
No — it’s built around a two-parent overnight split. For arrangements involving additional caregivers, calculate percentages manually by dividing each caregiver’s overnights by the combined total.
What’s considered a roughly equal custody split?
A 50/50 overnight split is the most literal even division, though family courts and state guidelines vary in how they define “shared” or “equal” parenting time, and some set a specific percentage threshold. Check your jurisdiction’s specific definition if it affects a support or custody determination.
