Capacity is consumed by complete frames
CAN traffic includes arbitration, control, CRC, acknowledgement, delimiters, payload, and intermission. This toolkit models 47 base bits for an 11-bit identifier frame or 67 for a 29-bit identifier frame, then adds eight bits per payload byte.
Bit stuffing makes length data-dependent
CAN inserts a complementary bit after five consecutive equal-polarity bits through the stuffed region. The actual count depends on the transmitted pattern. The calculator therefore reports an unstuffed baseline and a simple planning estimate adding 20% and rounding up; neither should be presented as an exact trace.
Average load is not latency
High-priority frames win arbitration, and bursts or error recovery can delay low-priority traffic even when average load is below 100%. Select an operating target from message deadlines and worst-case response analysis, not a universal rule of thumb.
Validate the design
Sum every periodic and event-driven stream, include diagnostics and boot traffic, then measure a stressed network with a CAN analyzer. Use a message-level timing analysis for safety-relevant systems.