08/20/2020: Updated version here (kurtextrem.de/sens5.html). The values below are not 100% correct.

   

Scope | Sens

1.0x:
1.5x:
2.0x:
2.5x:
3.0x:
4.0x:
5.0x:
12.0x:
08/19/2020:
Note: Currently, FOVs such as 4:3 are bugged on TTS.
This means we must wait for Ubisoft to fix it. Once they do, and if the formula needs a change, I will update this calculator.
I'll use Twitter (@kurtextrem) to communicate those updates.
Click to see GameSettings.ini [INPUT]:
AimDownSightsMouse=55 ADSMouseUseSpecific=1 ADSMouseSensitivityGlobal=50 ADSMouseSensitivity1x=38 ADSMouseSensitivity1xHalf=61 ADSMouseSensitivity2x=62 ADSMouseSensitivity2xHalf=62 ADSMouseSensitivity3x=63 ADSMouseSensitivity4x=63 ADSMouseSensitivity5x=63 ADSMouseSensitivity12x=97
Click to view the formulav1 beta or alternative formulas
x1 = ads * 0.7
x1.5 = ads * 0.9
x2 = ads * 1
x2.5 = ads * 1.05
x3 = ads * 1.075
x4 = ads * 1.09375
x5 = ads * 1.0984375
x12 = ads * 1.0999999046325684
Values found by LightleRyan and u/paradox12357.

Alternative Formulas:
Default: kurtextrem.de/sens.html
In case the values you get don't seem correct and they feel different, try this version: kurtextrem.de/sens3.html by CrossArchon.
Or this one: kurtextrem.de/sens2.html by me (using 3:2 aspect ratio).
P.S.: Don't like matching 360°/cm values? Try matching "Visuomotor" distance: Details, Calculator. Instructions:
1) Set to "Tom Clancy's Rainbow Six Siege"
2) Set "Hipfire Mouse Sensitivity" to "Virtual" & put in your usual Hipfire sens
3) Enter your FOV under Field of View: "Custom"
4) Then from the right side, take "Game Sensitivity" for your prefered sight over here to calc Shadow Legacy sensitivities.
TL;DR:
When matching 360°/cm distances, it doesn't factor in the felt (visual) distance you move on the screen. Visuomotor does, so hipfire and ADS feel similar on the screen.
Pre-Shadow Legacy: 40-45 (differs per FOV) matched the old ACOG, 71-73 the old 1x sights.
P.S.²: If one of your friends can't access this link, try this one instead: kurtextrem.de/sens.html. Some adblockers block "ads.html".
P.S.³: Values found by @LightleRyan and u/paradox12357. Calculator made with ❤️ by @kurtextrem (me).