The Oura Ring is recommended to be worn on the index finger, preferably the non-dominant hand's index finger, for the most consistent fit and optimal sensor performance. If the index finger doesn't fit well, the middle or ring fingers are the next best options, but large knuckles should be avoided to prevent the ring from getting stuck or being the wrong size. It is also common to switch fingers based on comfort, swelling, or activity, but having a primary finger for a snug fit is ideal.

Key Points on Wearing the Oura Ring

• Best finger: Non-dominant index finger
• Alternatives: Middle or ring finger (avoid large knuckles)
• Comfort: The ring should fit snugly, not too tight or loose
• Flexibility: It's fine to switch fingers for comfort during workouts or sleep
• Fit test: Wearing the sizing ring 24 hours including sleep ensures best size and fit

This advice comes from Oura's official sizing and support guides and user experience shared on forums.