Well first of all you can't put in decimals anymore, so you can't make it perfectly accurate. And other than that, for me aim sens was waaaaaaaaaaaay too high and I checked multiple times if I calculated it correctly. Right now it's fine for me, not perfect but I managed to manually get it pretty close. This is a very popular f2p game tho so I think lots of people would benefit from having a good calculator in the long run.
I'm not sure if it's possible though, I don't think it's possible anymore to put in decimals. Which seems like a huge failure on the design part of a big shooter game.