Ring Size Guide — US, UK & EU Conversion Chart

The most common cause of a remake is a ring sized from a guess. Ten minutes with a strip of paper beats any estimate from a photograph.

Measure an existing ring

Take a ring that fits the intended finger — not the thumb, not a ring worn on a chain.
Measure the inside diameter in millimeters with a ruler, across the widest point, inside edge to inside edge.
Match it in the chart below. If you fall between two sizes, take the larger one for wide bands.

Measure the finger

Wrap a strip of paper around the base of the finger, snug but able to slide over the knuckle.
Mark where it overlaps, lay it flat and measure to the millimeter — that is the circumference.
Measure at the end of the day, when fingers are largest, and at room temperature.

Conversion chart

US	UK	EU / ISO	Inside diameter	Circumference
4	H	47	14.9 mm	46.8 mm
5	J ½	49	15.7 mm	49.3 mm
6	L ½	52	16.5 mm	51.9 mm
7	N ½	54	17.3 mm	54.4 mm
8	P ½	57	18.1 mm	57.0 mm
9	R ½	59	18.9 mm	59.5 mm
10	T ½	62	19.8 mm	62.1 mm
11	V ½	65	20.6 mm	64.6 mm
12	Y	67	21.4 mm	67.2 mm

Wide bands fit tighter

Anything 6 mm wide or more needs roughly a half size up, because the band covers more of the finger and has less room to pass the knuckle. Comfort-fit interiors reduce this slightly but do not eliminate it. If you are ordering an 8 mm men’s band, tell us and we will adjust.

When the knuckle is wider than the base

If the ring must pass a knuckle more than 2–3 mm larger than the base of the finger, a hinged or open shank is more comfortable than sizing up. We make both. Ask before you order a full eternity band, which cannot be resized without a visible joint.

Free resizing

First resizing is free within 30 days on rings we made, up to two sizes, where the design allows. Eternity bands and full-pavé shanks generally cannot be resized — which is why we ask you to measure twice.