How do I calculate overtime on a 12-hour or DuPont rotation?
Compare the hours you worked with your monthly target from your contract, not with a count of shift days. The target is weekly hours × days in the month ÷ 7; overtime is worked hours minus that target. ShiftRoster does this for 12-hour and DuPont rotations on iPhone.
How to calculate it yourself
- Take your weekly contract hours, for example 40.
- Monthly target = weekly hours × days in the month ÷ 7. For 40 hours and a 30-day month: 40 × 30 ÷ 7 = 171.4 hours.
- Add up the hours you actually worked in the month. Fifteen 12-hour shifts = 180 hours.
- Overtime = worked minus target. Here 180 − 171.4 = 8.6 hours.
- Credit paid vacation and sick days as worked time, at the hours your contract says they count for.
- Carry the result forward month to month as a running balance (Stundenkonto).
The target comes from the contract, not from the number of shifts. A rest day then never raises the target, and working one adds real hours. Your employer or collective agreement may use a different reference period or rounding, so check it against your payslip.
The common DuPont pattern is 4 nights, 3 off, 3 days, 1 off, 3 nights, 3 off, 4 days, 7 off. That is 14 shifts of 12 hours in 28 days: 168 hours, or 42 hours a week on average.
How some shift calendar apps compare
| ShiftRoster | Supershift | Megashift | Dienstplan-Kalender | |
|---|---|---|---|---|
| Price | Free, EUR 5.99 once | Free + EUR 3.99/mo, 9.99/yr or 39.99 lifetime | Free + EUR 2.49/mo, 8.99/yr or 24.99 lifetime | Free + up to EUR 4.99 in separate one-time extras |
| 12-hour / off-day overtime | Computed from contract hours, free | A user review called off-day overtime math "broken" for real 12-hour shift workers (2★, 2026-08-31) | Not independently verified | Sold as a separate paid extra ("Extra 3 – Überstunden") |
Facts checked 2026-09-26 from each app's public App Store listing and reviews cited by date. "Not independently verified" means we did not install the competing app; it is not a claim the feature is missing.
ShiftRoster: a 12-hour calendar that uses contract hours
ShiftRoster projects 8-hour, 12-hour, DuPont or custom rotations onto a month calendar with rest days and public holidays for your German state. Hours and overtime are computed from your contract hours, with vacation, sick and training days credited.
Price: the calendar, hours and overtime, one Bundesland's holidays and the widget are free. A one-time EUR 5.99 unlock adds a pay estimate, iOS Calendar export, CSV month sheet and iCloud sync. No subscription, no account.
Coming soon to the App Store. Details on the ShiftRoster support page.
Frequently asked questions
What is the DuPont shift pattern?
A 28-day cycle of 12-hour shifts: 4 nights, 3 off, 3 days, 1 off, 3 nights, 3 off, 4 days, then 7 off. That is 14 shifts and 168 hours, or 42 hours a week on average.
Why does my shift app show strange overtime?
Some apps count shift days instead of comparing worked hours with your contract hours. On a 12-hour rotation with many rest days, that can give a target that makes no sense.
Is the ShiftRoster overtime calculation legally binding?
No. It is arithmetic on your contract hours and your shifts. Your employer's rules and any collective agreement decide what counts as overtime. ShiftRoster gives no legal, tax or payroll advice.
Is ShiftRoster free?
The rotation calendar, hours and overtime, one Bundesland's holidays and the widget are free. A one-time EUR 5.99 unlock adds the pay estimate, calendar export, CSV month sheet and iCloud sync. No subscription, no account.
Does ShiftRoster know my state's public holidays?
Yes, for all 16 German states, computed on your device. The free tier includes one Bundesland.
This page is arithmetic, not legal, tax or payroll advice. Your contract and any collective agreement decide what counts as overtime.