Start with a repeating pattern
Choose a pattern
Set the work days and days off, or the nights with each parent.
Choose the start date
Match that date to the first day of your repeating pattern.
Follow the dates
The pattern repeats through your chosen year.
A pattern is a short sequence that repeats. For example, DDDDOOOO means four work days followed by four days off, then the same sequence starts again.
- D
- Day shift
- N
- Night shift
- M
- Morning shift
- E
- Afternoon shift
- O
- Day off
- A/B
- The two parents in a custody pattern
M and E are used for patterns with three shifts a day. In 24/48, 48/96 and Kelly, D represents a 24-hour duty day.
See it on a calendar
Here is one crew working four days on, then four days off, starting on 3 January 2027. The first two dates stay blank because the pattern has not started yet.
| Sun | Mon | Tue | Wed | Thu | Fri | Sat |
|---|---|---|---|---|---|---|
| 1— | 2— | |||||
| 3D | 4D | 5D | 6D | 7O | 8O | 9O |
| 10O | 11D | 12D | 13D | 14D | 15O | 16O |
| 17O | 18O | 19D | 20D | 21D | 22D | 23O |
| 24O | 25O | 26O | 27D | 28D | 29D | 30D |
| 31O |
16 work days in January · 183 in 2027
What to look for
- January workdays
- 3 to 6, 11 to 14, 19 to 22 and 27 to 30
- January workday count
- 16
- 7 January
- off
- Workday count for 2027
- 183
Set the start date and crew offsets
The start date is the date of the first code in your pattern. Dates before it stay blank and are not included in the totals.
An offset moves another crew’s pattern by a number of days. This lets crews follow the same cycle at different points.
| January | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
|---|---|---|---|---|---|---|---|---|
| Crew A0-day offset | D | D | D | D | O | O | O | O |
| Crew B4-day offset | O | O | O | O | D | D | D | D |
Crew A works 3 to 6 January. Crew B follows four days later, working 7 to 10 January. D means work; O means off.
The exact rule for crew offsets
Pattern position = (date − start date − crew offset) modulo the cycle length.
“Modulo” means wrapping back to the start when you reach the end of the cycle. Negative positions wrap around too. Date differences use whole calendar days, rather than elapsed hours, so leap years and daylight-saving clock changes do not shift the repeating pattern.
Explore shift patterns
Choose a pattern to see one complete cycle. This is an explanation preview; your dates and crew names are set in the calendar tool.
4 on 4 off
Repeats every 8 days
- 4day shifts
- 4days off
Then the cycle starts again.
An 8 day cycle: 4 work days, then 4 days off. A second crew offset by 4 days works the days the first crew is off.
DDDDOOOODefault crew offsets: A 0, B 4 days.
Preset definitions
4 on 4 off
An 8 day cycle: 4 work days, then 4 days off. A second crew offset by 4 days works the days the first crew is off.
DDDDOOOODefault crew offsets: A 0, B 4 days.
DuPont
A 28 day cycle for 4 crews: 4 nights, 3 off, 3 days, 1 off, 3 nights, 3 off, 4 days, then 7 off. Each crew starts 7 days after the one before.
NNNNOOODDDONNNOOODDDDOOOOOOODefault crew offsets: A 0, B 7, C 14, D 21 days.
Pitman
A 14 day cycle: 2 on, 2 off, 3 on, 2 off, 2 on, 3 off. A second crew offset by 7 days works the days the first crew is off.
DDOODDDOODDOOODefault crew offsets: A 0, B 7 days.
Panama (14-day shift rotation)
A 28 day cycle for 4 crews, using the 2 on, 2 off, 3 on, 2 off, 2 on, 3 off rhythm. Work days in the first 14 days are day shifts; work days in the next 14 are night shifts. This is the 14-day shift-rotation variant documented by the Naval Postgraduate School. Check that your employer uses this variant.
DDOODDDOODDOOONNOONNNOONNOOODefault crew offsets: A 0, B 7, C 14, D 21 days.
2-2-3
A 14 day cycle of 2 on, 2 off, 3 on, then 2 off, 2 on, 3 off. It follows the same cycle as the Pitman schedule.
DDOODDDOODDOOODefault crew offsets: A 0, B 7 days.
24/48
A 3 day cycle: one 24-hour shift, then 2 days off. Three platoons, one day apart, cover every day.
DOODefault crew offsets: A 0, B 1, C 2 days.
48/96
A 6 day cycle: two 24-hour shifts in a row, then 4 days off. Three platoons, two days apart, cover every day.
DDOOOODefault crew offsets: A 0, B 2, C 4 days.
Kelly
A 9 day cycle of 24-hour shifts: on, off, on, off, on, then 4 days off.
DODODOOOOCrew offsets start at 0 days; change them for your rota.
3x12
A 7 day cycle with 3 shifts a week: on, off, on, off, on, then 2 days off. Starting on a Monday gives Monday, Wednesday and Friday.
DODODOOCrew offsets start at 0 days; change them for your rota.
Continental
A 28 day cycle for 4 crews: 7 mornings, 2 off, 7 afternoons, 2 off, 7 nights, then 3 off. Each crew starts 7 days after the one before.
MMMMMMMOOEEEEEEEOONNNNNNNOOODefault crew offsets: A 0, B 7, C 14, D 21 days.
Understand custody patterns
A and B stand for the two parents. Each letter is the parent who has that night’s stay. In a 2-2-3 pattern, each parent has seven nights over two weeks.
The annual totals count the nights actually assigned in your chosen year. Dates before the starting date are excluded. That is why an equal repeating cycle can still produce slightly different annual totals.
Handover times are separate from overnight ownership. Calendar files use the local times you enter, without a fixed time zone. Check the imported times and any exceptions against your agreement.
These are editable starting templates, not recommendations or universal legal standards. Check the sequence and starting weekday with your agreement.
Custody template definitions
2-2-3
A 2 nights, B 2, A 3; then B 2, A 2, B 3.
AABBAAABBAABBB2-2-5-5
A 2 nights, B 2, A 5, B 5.
AABBAAAAABBBBB3-4-4-3
A 3 nights, B 4, A 4, B 3.
AAABBBBAAAABBB5-2-2-5
A 5 nights, B 2, A 2, B 5.
AAAAABBAABBBBBAlternating weeks
A 7 nights, then B 7 nights.
AAAAAAABBBBBBBEvery other weekend
Start on A's Monday. B has Friday and Saturday nights in the first week; A has the other nights.
AAAABBAAAAAAAAHow totals are worked out
Workday counts come from the dates covered by the chosen pattern and year. A workday count is different from paid hours: shift length and unpaid breaks affect hours.
A repeating pattern does not automatically account for leave, overtime, swapped shifts or changes to a parenting agreement. Check the generated dates against your actual arrangements.
Work and shifts
Average hours from a cyclePaid hours, averaged across weeks and years.
First subtract any unpaid break from each shift. Multiply the paid hours per shift by the work days in one complete cycle.
- Average hours per week
- Paid hours per cycle ÷ days in the cycle × 7
- Average hours per year
- Paid hours per cycle ÷ days in the cycle × 365
| Unpaid break per shift | Hours per cycle | Hours per week | Hours per year |
|---|---|---|---|
| None | 48 | 42 | 2,190 |
| 30 minutes | 46 | 40.25 | 2,098.75 |
Convert break minutes to hours by dividing by 60. Calculations keep full precision and round only the final result to two decimal places.
These are cycle averages, using 365 days even in a leap year. Your dated calendar can give a different total. Leave, overtime and shift changes are not included.
Dated 12-hour and 8-hour shiftsScheduled hours assigned to each shift’s starting date.
- 3x12 calendar
- Each shift adds 12 scheduled hours.
- Continental calendar
- Each shift adds 8 scheduled hours.
Hours belong to the date the shift starts. For example, a shift starting on 31 January and ending on 1 February counts towards January.
The 3x12 tool can use three fixed weekdays or your own repeating day, night and off pattern. For a rotating pattern, average shifts per week = work days in the cycle ÷ cycle days × 7. Employer patterns differ, so the tool shows the average for the cycle you enter.
These are scheduled hours, not payroll hours or a measurement of time elapsed. The pattern follows calendar dates and entered local times; daylight-saving clock changes do not change these nominal totals.
Parenting
Parenting time percentagesEach parent’s share of scheduled nights.
Count each parent’s nights in one complete cycle. Divide that parent’s nights by all the nights in the cycle, then multiply by 100.
- Example: Parent B has 4 of 14 nights
- 4 ÷ 14 × 100 = 28.6%
- Estimated nights in a 365-day year
- 4 ÷ 14 × 365 ≈ 104 nights
This is an estimate from the repeating cycle. The tools keep full precision until the result is displayed. A dated calendar counts the nights actually assigned in that year, so holidays, leap years and part cycles can change the result.
These percentages do not determine legal rights or support obligations. Check the schedule against your agreement.
Parent changes and school pickupsParent changes and agreed school pickup times.
A handover is recorded when two neighbouring dates are assigned to different parents. Both dates must have an assigned parent. The first scheduled date is not itself a handover.
- Choose the ordinary handover time and place.
- Set school pickup details for the weekdays you select.
- Add no-school date ranges, including both the first and last date. During those ranges, the ordinary handover details apply.
Pickup details do not change which parent has the overnight stay. A full-cycle count includes the change into the next cycle; an annual list includes only handovers dated in that year.
The calendar file records each handover at its entered time, without assuming how long it takes.
Team rotas
Round-robin team allocationAssignments shared in the order names are entered.
- Names take turns in the order you enter them.
- Each selected weekday gets the next required number of names. Other weekdays do not advance the list.
- After the last name, the rota returns to the first. The selected end date is included.
A person is never assigned twice on the same date. Across the full date range, the highest and lowest assignment totals differ by at most one.
These totals count assignments, not hours, availability or workload. A separate rota starts again at the first name.
On-call blocks and year boundariesDaily or weekly blocks, including across New Year.
Names take turns in daily or weekly blocks. Each block starts at your local handover time and continues until the next handover, even across New Year.
- What counts towards the year’s total?
- Only blocks that start in that year.
- What if a block started in December?
- It is shown for January coverage, but belongs to the previous year’s start count.
Selecting another year keeps the same rota running from its original start date. Calendar downloads contain one timed event for each complete block, rather than separate daily events.
Use your calendar
Print and download options depend on the tool. Check your dates and names before exporting.
Print a paper copy
Choose Print in the tool. Review the A4 or Letter preview and the page count, then print the pages you need.
Add it to your calendar app
Download the calendar file (.ics) and import it into your phone or calendar app. Check the dates, times and time zone after importing.
The shift pattern generator offers one file per crew and a combined calendar. Files use all-day events unless shift times are set, with one event per block of days.
Sources and checks
The preset definitions on this page use the same patterns as the tools. The Panama preset follows the Naval Postgraduate School study below: a 28-day cycle, with day and night shifts changing every 14 days. Other versions exist, so check your employer’s rota.
Holiday tools use stored data from official government sources. They show their own source links, checked dates and regional coverage; the holiday data is not fetched live.
Sources
Last checked: