Drivers should not be doing this math on the shoulder. Truck Mode does it on the route.
Maximum driving time after 10 consecutive hours off duty.
Driving must end 14 hours after coming on duty, breaks included.
Required after 8 cumulative hours of driving without a 30-minute interruption.
Ten consecutive hours off duty restarts the 11 and 14 hour clocks.
HOS calculations are planning estimates only. The driver's ELD and official FMCSA rules remain authoritative.