Common custody schedules get name-dropped constantly in family court, mediation sessions, and parenting plan negotiations. The specific numbers behind them almost never get explained. A parent agreeing to "every other weekend plus midweek" probably doesn't realize that arrangement gives them 28.5% of the year with their child. Someone proposing alternating weeks may not know it produces 49.9%, not a clean 50%.
Those percentages matter. They determine whether you're above or below state child support thresholds, and they shape every financial and logistical conversation you'll have about your parenting arrangement.
Below are the six most common custody schedules, with the exact math behind each one.
How Schedules Translate to Percentages
The formula is straightforward. Count the overnights a parent has in a calendar year, divide by 365, multiply by 100.
(Overnights ÷ 365) × 100 = Parenting Time Percentage
The tricky part is the counting. A standard schedule may say "every other weekend" but the actual overnight count depends on whether the weekend runs Friday-to-Sunday (2 nights) or Friday-to-Monday (3 nights). Holiday agreements, summer blocks, and school break schedules all add to or subtract from the base count.
For a precise number, run your specific arrangement through the parenting time calculator rather than estimating. The difference between estimating and calculating can be consequential when you're near a state threshold.
Schedule 1: Every Other Weekend at 14.2%
Overnights per year: 52
The most traditional arrangement in American family courts. The child lives primarily with one parent and spends every other Friday evening through Sunday evening with the other. That's 26 weekends × 2 nights = 52 overnights per year.
52 ÷ 365 × 100 = 14.2%
This arrangement developed historically when courts defaulted to mothers as primary custodians and fathers received "visitation." It's less common as a default now. Most states apply a best-interests-of-the-child standard rather than a gender preference. But EOW remains appropriate in specific circumstances: when parents live far apart, when one parent has irregular work hours, when a child is very young and strongly attached to a primary caregiver, or when one parent has limited prior involvement.
At 14.2%, this schedule sits well below the shared-custody threshold in most states, which kicks in somewhere between 30% and 40%. Child support calculations on this schedule use the primary-custody formula.
Variation: Extended EOW
Some orders extend the weekend to Friday evening through Monday morning school drop-off, adding a third overnight. That brings the total to 78 overnights per year, or 21.4%, without changing the basic structure.
Schedule 2: Every Other Weekend Plus Midweek Night at 28.5%
Overnights per year: 104
Adding one Wednesday or Thursday overnight to the EOW baseline is a common modification. It meaningfully increases the non-primary parent's time without requiring 50/50 logistics.
52 (EOW) + 52 (weekly midweek night) = 104 overnights
104 ÷ 365 × 100 = 28.5%
This schedule is popular for school-age children because it maintains a primary home base (useful for homework routines, consistent school pickups, and extracurricular scheduling) while ensuring the child sees both parents multiple times per week. It's also a common intermediate step for families transitioning from EOW toward a higher-percentage arrangement.
At 28.5%, this schedule sits just below the shared-custody threshold in states like California (roughly 32%) and Texas (roughly 40%). Whether it crosses the threshold depends on how holidays and summer time are allocated in the full parenting plan.
Schedule 3: 50/50 Alternating Weeks at 49.9%
Overnights per year: 182 to 183
The simplest equal-time arrangement. One full week at Parent A's home, then one full week at Parent B's home, alternating throughout the year. Exchanges typically happen on Sunday evening or Monday morning.
182 ÷ 365 × 100 = 49.9%
The appeal is simplicity. Everyone knows exactly where the child is on any given day without consulting a complex calendar. Both parents get full weeks that include school nights, which matters for helping with homework, attending school events, and managing weekday routines.
The main drawback is the 7-day gap. Between exchanges, the child goes a full week without seeing the other parent. For younger children, that stretch can feel long. For school-age children and teenagers who benefit from settling into a routine, it works well.
Schedule 4: 2-2-5-5 Schedule at 49.9%
Overnights per year: 182
The 2-2-5-5 runs on a two-week rotation. Two days with Parent A, two days with Parent B, five days with Parent A, five days with Parent B. The pattern then repeats. Exchanges happen three to four times per two-week cycle.
A common version: Parent A has Monday and Tuesday, Parent B has Wednesday and Thursday, then parents alternate the long weekend (Friday through Tuesday). The following week flips.
182 ÷ 365 × 100 = 49.9%. Identical to alternating weeks on paper.
The 2-2-5-5 is particularly well-suited for younger children because the maximum separation from either parent is five days, not seven. The two-day stretches at the start of each cycle mean the child sees both parents multiple times each week. The tradeoff: more frequent handoffs, which require good co-parent communication and proximity.
Why Some Families Prefer 2-2-5-5 Over Alternating Weeks
If you have children under 8, child development professionals frequently recommend 2-2-5-5 over alternating weeks specifically because of the shorter maximum gap. The research on young children's attachment suggests that five-day separations are more manageable than seven-day ones.
Schedule 5: 3-4-4-3 Schedule at 49.9%
Overnights per year: 182
The 3-4-4-3 also runs on a two-week cycle but uses longer stretches. Three days with Parent A, four days with Parent B in week one. Four days with Parent A, three days with Parent B in week two. Exchanges happen twice per two-week cycle, less often than 2-2-5-5.
182 ÷ 365 × 100 = 49.9%. Again identical.
A typical 3-4-4-3 looks like this: Parent A has Monday through Wednesday, Parent B has Thursday through Sunday, then it flips. Exchange happens twice per week on the same days, which makes it very predictable.
The 3-4-4-3's lower exchange frequency is its key advantage over 2-2-5-5 for families with moderate communication challenges or geographic distance between homes. The four-day maximum stretch (rather than five with 2-2-5-5) also means neither parent goes too long without contact.
For school-age children who thrive on routine, the 3-4-4-3 produces a more settled schedule than the 2-2-5-5 because the transition days stay consistent week over week.
Schedule 6: Primary Custody at 90/10 or 85/15
Overnights per year: 36 to 54 for the non-primary parent
At the opposite end from 50/50, some arrangements place the child almost entirely with one parent. A 90/10 arrangement gives the non-primary parent about 36 overnights per year: roughly every other weekend with no midweek contact, or occasional school holiday time.
36 ÷ 365 × 100 = 9.9%
54 ÷ 365 × 100 = 14.8%
These arrangements are appropriate when one parent has serious concerns about the child's safety or wellbeing in the other home, when one parent has been largely absent, or when a parent's work or life circumstances make more time genuinely impractical.
Courts are reluctant to grant arrangements this lopsided without documented reasons. A parent seeking to limit the other parent to 10% or less needs to show why that's in the child's best interest, not just their own preference.
How to Calculate Any Custom Arrangement
The six schedules above cover most parenting plans. But plenty of families use custom arrangements that don't fit neatly into any single category. A schedule that gives one parent three weeknights per week plus alternating weekends produces a different percentage than any of the above.
The calculation method stays the same regardless of how unusual the schedule is:
1. List every overnight the child spends with each parent over 14 days (one full cycle)
2. Multiply by 26 to get the annual base count
3. Add any additional overnights from summer blocks or holidays
4. Divide the total by 365 and multiply by 100
Or skip the math entirely and plug your schedule into the parenting time calculator. It handles the annual calculation automatically, including holiday and summer adjustments, and gives you a precise percentage you can use in negotiations or legal filings.
Knowing your exact percentage, not a rough estimate, is worth the few minutes it takes to calculate. When you're near a state threshold, the difference between 29% and 32% can change a child support calculation by hundreds of dollars a month.