If measuring and marking to find your ring size on your own isn't for you, there are also online sites that offer a different way to size your finger. Do an Internet search engine search for "online ring sizer" to find a site that works for you.
A site with an actual online ring sizer will have a piece of paper with various ring sizes on it. The site will ask you to print out the paper with the ring shapes on it. When done printing you will need to cut out each ring shape's circle. Underneath each ring shape should be the ring size that goes with the shape. After cutting out the inside of each ring shape, you will need to stick your finger into the ring holes until your finger fits perfectly in a hole. This hole should represent your ring size. The majority of online ring size sites offer this information free!