PNB Calculator
Enter a duty start and finish time to work out the shift length, midpoint, earliest valid PNB start, latest valid PNB finish, and turn length checks. Actual PNB start and finish are optional.
DRI rule summary: duties up to 5h 59m may have a PNB at any point, including at the start or finish. Duties of 6h or more must not have the PNB before work starts or after all work is complete, and the single PNB, or one of the 2 PNBs where 2 × 20 minutes is used, must be within 2 hours of the midpoint.
Enter duty times
Reminder: 2 × 20-minute breaks may only be diagrammed for turns of less than 08:45, unless agreed locally.
Overnight duties are supported. If the finish time is earlier than the start time, it is treated as the next day.
Results
No result yet.
Earliest valid PNB start
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Time inside midpoint window
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Start
Midpoint window / actual PNB
End
Enter times and press Calculate.
Disclaimer: this calculator is an informal guide only and is not an official company, union, legal, payroll, or roster-planning tool. It is based on a practical reading of the DRI, but actual diagramming may differ because of local agreements, operational requirements, continuous driving limits, disruption, or the clause allowing different placement where using the midpoint rule would increase the overall number of diagrams required. Always check the current DRI, local agreements, and the appropriate manager or union representative before relying on the result.