Ring Size Guide

FORM & KIN uses US ring sizes. The most reliable method is to have the intended finger measured by a professional jeweler.

Measure at home

1. Measure the inside diameter of a ring that fits the intended finger; or wrap a non-stretch string or thin paper strip comfortably around the base of the finger and measure its length.
2. Match the closest measurement below. The chart includes both millimeters and inches.
3. Measure at the end of the day, when fingers are warm. If you are between sizes, or selecting a wider band, consider the next half size up.

US ring size chart

US size	Inside diameter	Inside circumference
3	14.1 mm / 0.555 in	44.2 mm / 1.740 in
3.5	14.5 mm / 0.571 in	45.5 mm / 1.791 in
4	14.9 mm / 0.587 in	46.8 mm / 1.843 in
4.5	15.3 mm / 0.602 in	48.0 mm / 1.890 in
5	15.7 mm / 0.618 in	49.3 mm / 1.941 in
5.5	16.1 mm / 0.634 in	50.6 mm / 1.992 in
6	16.5 mm / 0.650 in	51.9 mm / 2.043 in
6.5	16.9 mm / 0.665 in	53.1 mm / 2.091 in
7	17.3 mm / 0.681 in	54.4 mm / 2.142 in
7.5	17.7 mm / 0.697 in	55.7 mm / 2.193 in
8	18.1 mm / 0.713 in	57.0 mm / 2.244 in
8.5	18.5 mm / 0.728 in	58.3 mm / 2.295 in
9	18.9 mm / 0.744 in	59.5 mm / 2.343 in
9.5	19.4 mm / 0.764 in	60.8 mm / 2.394 in
10	19.8 mm / 0.780 in	62.1 mm / 2.445 in
10.5	20.2 mm / 0.795 in	63.4 mm / 2.496 in

Millimeter measurements are rounded to one decimal place and inch measurements to three decimal places. Slight differences can occur between sizing tools. For a gift or an uncertain fit, please contact us before ordering.