First of all sorry if this post is repeated but I couldn't find something similar. I want to know the formula to calculate Gear Score or if I can download and AddOn to the game without getting ban and where can I download it.
Thank you so much and sorry if the question is repeated .
Well first of all gearscore is not a part of world of warcraft, it was an added addition only visible with an add-on. So you shouldn't be in any trouble of using a gear score addon as its the only way to actually know how much gear score you have.
There is no such thing as an addon that can get you banned.
Weeeeeeeeeeeeeeeeeeeell, in the past I had to help a guy, whose account got banned due to botting, and he speculated that an addon had been the main culprit. Believe me, I asked him several times whether he had downloaded any cheating programs or have visited phishing sites, and he convinced me that he hadn't done such things. The only thing he had done prior to that occurrence had been downloading a certain addon (Tellmewhen from gnarlyguides). He had written a lot of ban appeals, and Smyth had found traces of illegal programs in his account.
I can only speculate what actually triggered the Sentinel Anti-Cheat system. I am aware that it's really strange to think that an addon could have caused such damage to his account, but MAYBE there had been a trojan horse or a malicious code inside, which he overlooked. I mean, there was a similar case where a fanmade DBM addon was able to delete one's gear and dismantle a whole guild:
So, yeah. People need to be careful where they download their addons from.
@ OP - Addons are allowed, as long as you don't use programs that inject certain codes into the client. The one you are looking for is "GearScore". Keep in mind that it can bug at certain times, and you might want to disable it prior to some raids.