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INThe 21 On 7 Off Roster: How the 3-and-1 Swing Works
The 21 on 7 off roster (the '3 and 1' swing) has crews work twenty-one consecutive shifts followed by seven days off. It is a maximum-intensity remote-site rotation — at 12-hour shifts it averages roughly 63 hours a week — used where projects want crews on site for the longest stretch sustainable.
Try the rotation
Pick a start date to map the rotation onto real weeks. Team A starts the cycle on day 1; the other teams are staggered so cover never drops.
| Mon | Tue | Wed | Thu | Fri | Sat | Sun | Mon | Tue | Wed | Thu | Fri | Sat | Sun | Mon | Tue | Wed | Thu | Fri | Sat | Sun | Mon | Tue | Wed | Thu | Fri | Sat | Sun | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Team A | Day | Day | Day | Day | Day | Day | Day | Day | Day | Day | Day | Day | Day | Day | Day | Day | Day | Day | Day | Day | Day | Off | Off | Off | Off | Off | Off | Off |
The math
| Cycle length | 28 days |
|---|---|
| Shift length | typically 11–12 hours |
| Shifts per cycle | 21 |
| Average hours per week | ~58–63 hours — a maximum-intensity roster |
| Off block | 7 consecutive days per cycle |
How the rotation works
The 3-and-1 swing pushes the FIFO equilibrium toward production: three-quarters of the year on site, travel amortised over a 28-day cycle, and the project gets long uninterrupted runs from each crew. It exists mostly in construction phases, shutdowns and remote projects with hard deadlines — and in roles where the daily load is more supervisory than physical.
The arithmetic deserves plain statement: 21 twelve-hour shifts is 252 hours per cycle — about 63 a week — and no roster sustains that without consequences unless fatigue is engineered around: shift length trimmed (11s and 10.5s are common), duties rotated within the swing, mid-swing rest structured, and the week off treated as inviolable. Many operators use 3-and-1 only for defined project phases before stepping crews back to 2-and-2.
Who uses it
- Remote construction & shutdowns — deadline phases that justify maximum-intensity swings
- Mining project & expansion crews — 3-and-1 during build, 2-and-2 in steady state
- Camp management & catering — long swings where the work is steady rather than heavy
- Drilling & exploration — short campaign seasons compressed into long rotations
Pros & Cons
Pros
- Maximum on-site continuity for deadline-driven projects
- One travel rotation per 28 days
- A full week off every cycle, predictable a year ahead
- Pay accumulates fast — the roster's honest attraction
Cons
- ~60+ hour weekly average is at the limit of sustainability
- Fatigue by week three is significant and must be actively managed
- One week off barely clears sleep debt before the next swing
- Family and social life run on one week in four
Variations & alternatives
Free template download
Download the pre-built rotation calendar, ready to print or edit. No email required.
Build this schedule in Tommy
Set the rotation once and Tommy fills the weeks ahead — shift swaps, leave and coverage gaps handled in one place, with your team always seeing the latest version.
