Shift Pattern Calculator

Pick your rotation, tell it one date you were on, and it works out the rest — every working day, every day off, your next day off, and how many full weekends the pattern actually gives you. Nothing to sign up for.

Your roster is the authority. This calculates the pattern you picked. Departments run local variations, rotate in different directions, and layer overtime, callbacks, court and training days on top. Use this to see the shape of the rotation, then check your own shift bid or roster for the specifics.

How these rotations actually work

Every repeating shift pattern is arithmetic. The cycle has a fixed length, you sit somewhere in it, and every future date is already determined. The only thing that makes it feel unpredictable is that most cycle lengths don't divide evenly into a seven-day week.

That single fact explains most of what people find frustrating about their roster:

• Cycles that divide by seven keep your days off still. The 2-2-3 Pitman runs on fourteen days, and fourteen is two weeks exactly — so your off days land on the same weekdays every fortnight, and a three-day weekend comes round every other week.
• Cycles that don't divide by seven make your days off travel. Four on, four off is an eight-day cycle. Three on, three off is six days. Both slide forward through the week, which is why a standing Tuesday commitment is impossible and why you get a full weekend roughly one time in four.
• Longer cycles trade little rests for one big one. DuPont packs twenty-eight days into a rotation that ends with seven consecutive days off — the longest block most shift workers ever see without booking leave.

Common questions

How do I calculate a 4-on-4-off schedule?
It repeats every eight days, so one known date fixes all the others. Count the days since a date you worked, take the remainder after dividing by eight, and days 0–3 are on while days 4–7 are off. The calculator above does it and prints the calendar.

Why do my days off land on different weekdays each cycle?
Your cycle length doesn't divide evenly by seven. Eight-day and six-day cycles slide forward through the week. A fourteen-day cycle like the Pitman doesn't, which is why those rosters feel so much more predictable.

How many weekends off does 4-on-4-off give you?
About one full Saturday-and-Sunday in four, because the block keeps moving. A 2-2-3 gives you a three-day weekend every other week instead. Set the range above to 12 months and the calculator will count them.

Is this accurate for my department?
It's accurate for the pattern you select. Your employer's roster is still the authority — local variations are common, and nothing here knows about your overtime, callbacks or court days.