In the game you find the setting under Settings → Mouse & Keyboard → Sensitivity X and Y.
Set X and Y sensitivity to the same percentage.
Conversion
Apex Legends to Fortnite Sensitivity
In short: Apex Legends sens times 3.96. 1.2 becomes 4.8%. For your own value, just edit the sentence below.
How to set it in Fortnite
What changes when you go from Apex Legends to Fortnite
Apex Legends turns 3.96 times further per mouse count than Fortnite. That is why the number gets bigger while your mouse distance stays the same.
Fortnite shows 25.5° less field of view than Apex Legends by default (80° against 105.5°). The picture looks a little tighter and movement on screen a little faster. For Apex Legends the field of view is only a rough guide, check it in the game.
In Fortnite you can enter up to 1 decimal place. Use all of them to keep the conversion exact.
Common questions
How do I convert Apex Legends sens to Fortnite?
Multiply your Apex Legends sens by 3.96. 1.2 in Apex Legends becomes 4.8% in Fortnite.
Where do I set the sens in Fortnite?
Settings → Mouse & Keyboard → Sensitivity X and Y. Set X and Y sensitivity to the same percentage.
Why does Fortnite still feel a bit different?
Apex Legends: Slider from 70 to 110 (about 105 to 106° horizontal at 90). Fortnite: Default 80°, check in the game whether you changed it. 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.