20 mm ring size

The 20 mm ring size, measured straight across the inside, is about a US 10¼. In the UK it is U, and in Europe 63, and the ring is 62.8 mm round the inside.

20 mm ring size in every system

20 mm ring size: every system
US and Canada	about 10¼
UK, Ireland, Australia	U
Europe (EU)	63
Japan and China	21
India	23
Italy, Spain, Switzerland	23
Across the inside	20.0 mm · 2.00 cm · 0.787 in
Around the inside	62.8 mm · 6.3 cm · 2.47 in

Every half millimetre is a little over half a US size, so a 19.5 mm or 20.5 mm ring is the next size down or up. All of these numbers are from the standard ring size conversion table.

See a 20 mm ring at its real size

1Match a bank card

The card works like a ruler: nothing on it is read or saved, and a driving licence works too. Only its height counts, so the drawing may run off the edge of a phone. Hold the card flat on the screen, long side across, with its top edge on the drawing's top line. Then move the slider until the drawing's bottom line meets the card's bottom edge.

Optional. Only needed to lay a ring or strip on the screen; typed measurements work without it. Nothing on the card is read or saved.

2Measure

A ring I own My finger Print a sizer

Inside diameter of your ring mm

Lay the ring on the circle, or type the inside diameter if you measured it.

Length of your paper strip mm

Wrap a thin strip of paper around the base of your finger, mark where it overlaps, then measure to the mark.

The circle shows a 17.3 mm ring, drawn for a typical screen.

This size, drawn on your screen

US10¼

UK U · EU 63 · Japan 21 · India 23

20.0 mm (0.79 in) across the inside · 62.7 mm (2.47 in) around

Between US 10 and 10½? Choose 10½, the bigger one, especially for a wide band.

See every size in the ring size chart · Convert a size you already know

Nearby sizes

Too tight or too loose? Try the size one row up or one row down.

Nearby sizes
US and Canada	UK and Australia	Europe (EU)	Inside diameter (mm)	Circumference (mm)
9¼	S	60	19.2	60.2
9½	S½	61	19.4	60.8
9¾	T	61	19.6	61.4
10	T½	62	19.8	62.1
10¼	U	63	20.0	62.7
10½	U½	63	20.2	63.4
10¾	V	64	20.4	64.0
11	V½	65	20.6	64.6
11¼	W	65	20.8	65.3

Your questions on a 20 mm ring

How long is the inside of a 20 mm ring, measured all the way round?

Round the inside it is 62.8 mm, which is 6.3 cm. Straight across, it is 0.79 inches.

Which US ring size matches 20 mm across?

It is close to a US 10¼. In the UK that ring is U, and in Europe 63.