For freshly create accounts that have never played in the beta, the calculator is accurate.
But the calculator is inaccurate for accounts that have participated in the beta. I've confirmed this on two beta accounts, and one freshly made non-beta account (all with mouse smoothing disabled in input.ini file) Apparently the mouse sens values are stored server side, and something wonky is going on if you've played in the beta before.
For example,
Fresh account, calculator says 73 sens for 20cm 360. 1600dpi, 100fov. very accurate.
Beta account, calculator says 73 sens, which actually gives me like a 35cm 360. I have to use 100 sens to get around 20cm 360. I used a retractable tape ruler to measure this.
Anyone else who was in the Beta getting the same issue? Honestly not a huge problem, f2p game, easy to make new accounts.