You can wear the Oura ring on any finger, on either hand. The index, middle, and ring finger usually work best.
The ring should feel comfortable – especially in the morning when your fingers are slightly larger. The sensor bumps should be underneath your finger. When you try on the ring sizers, make sure your hands are warm.
If you're between sizes, we usually recommend choosing the smaller size. If you have big knuckles, choose the smallest size that slides over your knuckle.