Calculator
RS-485 Distance Planning Estimate
Change the inputs; results update automatically.
Formula
Approximate length = 1200 × √(9600 / baud) m Worked example
Use the estimate as a starting point, then verify the cable and devices against the manufacturers’ communication limits.
Scope and interpretation
This is a planning heuristic, not an RS-485 guarantee. Transceivers, cable, topology, noise and termination determine usable distance.