In order to convert Valorant sens to csgo, I tried changing fov in csgo(sv_cheats 1). I found that fov_cs_debug 86.631971 is same fov with Valorant 103 fov(found it with mouse-sensitivity.com converter), so I put that value in converter and got the sens 0.981739(my valorant sens is 0.297). I made sure that my zoom sens is set to 1.

I used that sens and fov for a long time to warm-up, but recently found that something is wrong. I tried sensitivity matcher to check my sens is same with valorant, but it was little bit slow. I changed my sens, and found that 0.988953 sens is exactly same with valorant sens 0.297. Why is this happening? Is this the problem of converter or mine?

It's a problem with the converter. 86.631971 should be getting rounded down to 86, and that would give you 0.9889534884 instead.

I've fixed this rounding issue now.