4 on 4 off is four 12-hour shifts in a row, then four full days off, repeating on an 8-day cycle. Because the cycle is one day longer than the week, every block starts one weekday later than the last. Your Monday start becomes a Tuesday start, then a Wednesday start, and around it goes all year. That drift shapes everything else about the pattern.
We make Lumical, an app that scans work rosters into your calendar, so read this with that in mind. Everything below is calendar math you can verify on our free shift pattern visualizer.
The drift is the feature
A rotation like 2-2-3 is 14 days long, divides evenly into weeks, and locks every crew to the same weekdays all year: one alignment gets 26 full weekends off, another gets none. 4 on 4 off cannot lock. The one-day slide walks your off-block through every position in the week over eight cycles, so the good and bad weekends spread across every crew.
Nights are the exception to that fairness. A Friday night shift ends on Saturday morning, so a night crew loses weekends that look free on the grid. The Friday night rule covers that trap.
No crew gets lucky and none gets stuck. Compare that with a Monday to Friday job, which keeps all 52 weekends, or with the locked rotations where the answer is 26 or 0 forever.
What a 4 on 4 off month looks like
This is October 2026 for a day crew, assuming cycle day 1, the first shift of a block, falls on Thursday 1 October 2026.
| Mon | Tue | Wed | Thu | Fri | Sat | Sun |
|---|---|---|---|---|---|---|
| 1 Day | 2 Day | 3 Day | 4 Day | |||
| 5 Off | 6 Off | 7 Off | 8 Off | 9 Day | 10 Day | 11 Day |
| 12 Day | 13 Off | 14 Off | 15 Off | 16 Off | 17 Day | 18 Day |
| 19 Day | 20 Day | 21 Off | 22 Off | 23 Off | 24 Off | 25 Day |
| 26 Day | 27 Day | 28 Day | 29 Off | 30 Off | 31 Off |
Four blocks start inside the month, and each one starts a day later than the one before: Thursday, Friday, Saturday, Sunday. That is the drift on one screen. It also means work touches every weekend in October except the last one: the 3rd and 4th, the 10th and 11th, the 17th and 18th, and then Sunday the 25th.
Free weekends come in clusters, not evenly spaced. The weekend of 31 October is clear, and so are the two after it, 7 and 8 November and 14 and 15 November. Then the run ends and work starts landing on Saturdays again.
Hours: where the 42 comes from
Four 12-hour shifts per 8 days is 48 hours per cycle. Scale that to a 7-day week and you get 42, which is why contracts quote 4 on 4 off as a nominal 42-hour week. No single week actually contains 42 hours. Any calendar week holds three or four of your shifts, so you work 36 hours some weeks and 48 in others, and only the average is 42.
How that lands over a full year, and why your own count can differ from your contract by a shift or two, is worked out in how many days a year is 4 on 4 off.
When a calendar beats the math
You do not need to memorize any of this. The 4 on 4 off calendar for 2026 lays out the full year for any starting position, and the 2027 calendar is there when your roster rolls over. The interactive visualizer also charts 4 on 4 off against Pitman, DuPont, and the rest on full weekends off, and exports the comparison as a PNG.
To see how the month above would read on a different rotation, rotating shift schedule examples runs six patterns over the same four weeks.
Where an app earns its place
Fair is fair: a clean 4 on 4 off runs on autopilot, and a paper year planner covers it if you sit down once and mark out the drift. The trouble is the real version: a swap here, overtime there, a training day mid-block, all delivered as a photographed grid. Lumical reads that photo, understands the rotation, and files every shift on the correct days, overnights included. You review everything before it saves. Getting a photo of a schedule into Apple Calendar walks through it step by step.
Working 4 on 4 off from a printed roster? Get Lumical on the App Store and put the whole month in your calendar from one photo.