Don’t measure when your body temperature is either too cold or too hot. A cold finger shrinks while a hot finger expands causing an inaccurate reading. Only measure when fingers are at room temperature.
If you hesitate between two sizes, always go with the larger one.
Extra wide band styles tend to run slightly small. If your ring has a narrower band than the one you wish to purchase, you may wish to order a ring a size larger than the size you normally wear.
When measuring your finger, always refrain from using a string; they tend to stretch, which can result in wrong size. ALWAYS use a paper strip about 1/2 inch width.
If your knuckle is a lot larger than the base of your finger and you’re using a paper strip, measure both the base of your finger and your knuckle and select a size in between the two.