So you have chosen a secret mission of purchasing a special Hare-y-gr-Owl-er ring and then remembered you dont know the size you need. Fear not, I have predicted your position and created a solution. ikr.
Follow this link : ring size me
Using this chart you can place an existing, well fitting ring over the size circles and voila, you have the size info to successfully order the ring you desire. It is important to deselect ‘fit to page’, etc and print the sheet at the actual size. You can check this using the scale rule with a physical ruler and match the 3″ line.
Best of luck and leave the making to me, i’ll do a fine piece for you. ~ the Growler of Cambridge.