To find your ring size, start by measuring the circumference of your finger using a piece of string or a flexible measuring tape. Wrap it around the base of your finger, making sure it's snug but not too tight. Mark where the string overlaps, then measure the length with a ruler. You can then compare this measurement to a ring size chart to determine your size. For the best fit, consider measuring your finger at the end of the day when it’s likely to be at its largest.