The quick answer: custody percentages are just overnights in disguise. Courts count the nights a child sleeps at each home across a year and divide by 365. So 50/50 means about 182–183 overnights each, every other weekend means about 52 overnights (14%), and the familiar labels in between — 60/40, 70/30, 80/20 — each have a night count you can check. This guide converts every common schedule, shows how the rotations actually differ, and explains why holidays move the real number more than the rotation does. When you want your own dates counted exactly, the free custody schedule calculator builds the full year calendar for you.
How the counting works
An overnight is a night the child sleeps at a parent’s home — or in that parent’s care, for example on a trip with them. Almost every US state’s child support guidelines count parenting time this way, because a night is a fact: it either happened at one home or the other. The IRS uses the same test in Publication 501 to decide which parent is the custodial parent for tax purposes. The one big exception is California, which measures timeshare as a percentage of hours instead. Two consequences follow. First, a dinner visit, however lovely, adds zero overnights. Second, schedules that sound similar can be far apart in nights — and schedules with different names can be identical.
The conversion table: percentages to overnights
| Parenting-time share | Overnights per year | What produces it |
|---|---|---|
| 50% | 182–183 | 2-2-3, 2-2-5-5, 3-4-4-3, week on/week off |
| 43% | About 156 | The 4-3 build, usually called 60/40 |
| 40% | 146 | An exact 60/40 |
| 30% | About 109–110 | An exact 70/30 |
| 29% | About 104 | Every other weekend + a weekly midweek overnight, or every weekend |
| 21% | About 78 | Every other weekend, extended to Monday morning — often called 80/20 |
| 20% | 73 | An exact 80/20 |
| 14% | About 52 | Every other weekend (Friday–Sunday) |
Read the table from your own situation. If a proposal says “70/30”, the honest question is: which build, and how many nights? The label is a nickname; the overnight count is what feeds support calculations and planning.
The 50/50 family: same nights, very different weeks
Four rotations dominate equal-time plans. All four give each parent 7 of every 14 nights, so the choice between them is not about quantity — it is about stretch length and exchange load.
| Schedule | Longest stretch | Exchanges per 2 weeks | Usually suits |
|---|---|---|---|
| 2-2-3 | 3 nights | 6 | Toddlers and preschoolers |
| 2-2-5-5 | 5 nights | 4 | School-age children; fixed weekdays |
| 3-4-4-3 | 4 nights | 4 | Ages roughly 4–10; the middle path |
| Week on / week off | 7 nights | 2 | Older children and teens |
The pattern is simple: the younger the child, the shorter the stretch and the more exchanges a family accepts. Many families climb this ladder as children grow — 2-2-3 for the preschool years, 2-2-5-5 or 3-4-4-3 through primary school, alternating weeks for teenagers.
The in-between splits: 60/40 and 70/30
Not every family can or should split time equally. The 60/40 is usually built as a 4-3: one parent keeps the school-week base and the other takes a long weekend (Thursday to Sunday) every week — about 156 overnights a year, roughly 43% for the parent with less time. The 70/30 has two standard builds: every other weekend plus one midweek overnight every week, or simply every weekend. Both give about 104 overnights (29%) — just under an exact 30% (about 110), and close enough that courts treat them as 70/30. These splits matter financially as well as emotionally: many states’ support formulas begin adjusting somewhere between about 90 and 128 overnights, so a 70/30 parent is typically past the line and an every-other-weekend parent is not.
Every other weekend, honestly counted
The every-other-weekend schedule is the most common starting point — and the most commonly misjudged. Friday evening to Sunday evening sounds like three days; counted in overnights it is two nights a fortnight, about 52 nights a year, 14%. Extend the return to Monday morning and it becomes about 78 nights (21%) — the arrangement often nicknamed 80/20. Neither figure includes a single holiday. Which brings us to the layer that changes everything.
Holidays and summer: the layer that moves the real number
Take the every-other-weekend parent at 52 overnights. Now add the standard layers most parenting plans include: alternating Thanksgiving and spring break (about 8–10 nights a year on average), half of winter break (about 5–7), and a summer block of two to four weeks (14–28). Their real total lands around 73–88 overnights — 20–24%, not 14%. The same effect, smaller, applies to every schedule: holiday layers routinely move a split by three to ten percentage points. This is why comparing rotations without dates is only half the job, and why the calculator applies your holiday and summer dates directly onto the calendar before it counts — and lets you compare two schedules with the same holidays applied to both, so the comparison is fair.
Choosing by the child in front of you
Schedules are usually chosen on three things: the child’s age, the distance between homes, and how well the parents can hand over. Under-fives generally do better with short stretches (2-2-3, 3-4-4-3). School-age children benefit from predictability (2-2-5-5’s fixed weekdays are built for this). Teenagers, with jobs, sports and opinions, usually prefer the calm of alternating weeks or a 4-3. Long distances rule out anything with midweek moves. And whatever you choose, write the holiday rules down — most “schedule problems” are really holiday problems that nobody specified.
Count your schedule on your real dates — free
Questions people ask
How many overnights is 50/50 custody?
182 or 183 overnights per parent per year. Every common 50/50 rotation gives each parent 7 of every 14 nights; who gets the extra night depends on the starting parent and leap years. Holidays then move the real figure a few nights either way.
How many overnights is 70/30 custody?
About 110 overnights for the parent with less time (30% of 365) and about 255 for the other. The two standard builds — every other weekend plus a weekly midweek overnight, or every weekend — give about 104, which is treated as 70/30 in practice.
How many overnights is 60/40 custody?
About 146 overnights for an exact 40%. The common 4-3 build (three nights every week with one parent) gives about 156, roughly 43% — close enough that courts and mediators still call it 60/40.
Why do courts count overnights instead of hours?
Because nights are objective and verifiable: a child either slept at a home or did not. Almost every state's child support guidelines use overnights, and the IRS uses the same nights test (Publication 501) for the custodial-parent question. California is the main exception, measuring timeshare in hours.
This guide is general information, not legal advice. Custody law, holiday conventions and counting rules vary by state and by your court order; some states average alternating holidays over two years. For anything you intend to file, take your printed calendar to a family-law attorney or mediator.
More articles
Bronze vs Silver vs Gold: Which Health Plan Actually Costs Less?
Premiums are only the start. Deductibles, copays and the out-of-pocket maximum decide what a year of care really costs on each metal tier.
Read guide →
How Much Will My Social Security Check Be in 2027?
The 3.6% COLA, the Medicare Part B bite, and the exact January dates your first bigger check arrives.
Read guide →
Christmas Shipping Deadlines 2026: Last Days to Ship
The plain-language US and UK last posting dates for gifts, carrier by carrier.
Read guide →