RS-485 Differential Pair Trace Width and Spacing Calculation for MAX485E on 2-Layer FR-4

Dear Forum, I have doubt how to length mathing (if necessary, idk if it is really necessary). Iam checking a layout board in my company and looking on it I realized theres a mismatch for RS-485 communication using chip MAX485E. So I have a connector which I will read MODBUS using RS-485 protocol and looking on MAX485E datasheet it says that differential driver output R= 27ohm (RS-485) I think it means I need to do length matching for this impedance, but how to calculate it using Saturn calculator, for instance or any other calculator like Kicad calculator?. I would like to know how to calculate trace width and gap to route differential pair in this situation. I have a 2 layers board, using FR-4 (Er=4.6) ; TanD = 0.02 ; Height of substrate (thickness): 1.6mm ; Rhou = 1.72e-08. Im using Kicad with diff pair width = 0.2mm and width gap = 0.25mm set as default in Software. If someone have any document to help me about theory too gonna be good. THanks

Didian,In most cases, you don't need to worry as much about length matching on a RS-485 signal as you would on Ethernet since the signal rate is generally much lower.
In general, if the additional delay caused by the extra trace length on one side is a small fraction of the bit time, you should be OK.

Didian
I completely agree with Elizabeth.However for future reference you should know there are tools which cover the type of question you are asking about (and much more), right here on EEWEB. See here