2. Measure a Ring You Already Have
If you have a ring that already fits your finger well, you can use a ruler to measure the inside diameter of this ring. Just take your ruler and measure straight across the inside of the ring from edge to edge. Take the diameter measurement in millimeters, and then use our measurement-conversion chart to find your ring size.
3. Print Out Our Paper Ring Sizer
You can also print out our ring sizer below from your computer at home. When printing the guide, make sure your print scale is set to 100 percent and the “fit to page” box is left unchecked in order to get an accurate measurement from the printout. Place the ring on the circles of this easy-to-use Ring Sizing Guide until you find the size that matches, or cut out the pre-measured strip of paper and use it to measure your finger.
Print our ring sizer Here