In the game you find the setting under Settings → General → Mouse → Sensitivity: Aim.
Conversion
Fortnite to Valorant Sensitivity
In short: Fortnite sens times 0.0794. 6% becomes 0.476. For your own value, just edit the sentence below.
How to set it in Valorant
What changes when you go from Fortnite to Valorant
Valorant turns 12.6 times further per mouse count than Fortnite. That is why the number gets smaller while your mouse distance stays the same.
Valorant shows 23° more field of view than Fortnite by default (103° against 80°). The picture looks a little wider and movement on screen a little slower.
In Valorant you can enter up to 3 decimal places. Use all of them to keep the conversion exact.
Common questions
How do I convert Fortnite sens to Valorant?
Multiply your Fortnite sens by 0.0794. 6% in Fortnite becomes 0.476 in Valorant.
Where do I set the sens in Valorant?
Settings → General → Mouse → Sensitivity: Aim.
Why does Valorant still feel a bit different?
Fortnite: Default 80°, check in the game whether you changed it. Valorant: 103° horizontal. Match the field of view as closely as you can; then the converted sens feels most natural.
Does this also apply to scopes?
No. The values are for hipfire. Zoom and scope sensitivities are set separately in the game.
Should I change my DPI?
No. Keep your DPI and only change the sens in the game. That keeps your feel the same everywhere.