Eve’s green fertile days on calendar

I notice on the period calendar that eve shows your fertile days in green on the calendar. I have been tracking my period for about a year now and noticed that the fertile days are always 2 weeks before my next period. I know typically that is common, but I wanted to know if anyone knew if eve just automatically tracks your fertile days as the 2 weeks before next period or it’s doing this based off my input into the app. Just curious to see if I can track my actual ovulation on here because I have very irregular periods.