17.5 mm ring size

The 17.5 mm ring size, measured straight across the inside, is about a US 7¼. In the UK it is O, and in Europe 55, and the ring is 55.0 mm round the inside.

17.5 mm ring size in every system

17.5 mm ring size: every system
US and Canada	about 7¼
UK, Ireland, Australia	O
Europe (EU)	55
Japan and China	14 to 15
India	15
Italy, Spain, Switzerland	15
Across the inside	17.5 mm · 1.75 cm · 0.689 in
Around the inside	55.0 mm · 5.5 cm · 2.16 in

Every half millimetre is a little over half a US size, so a 17.0 mm or 18.0 mm ring is the next size down or up. All of these numbers are from the standard ring size conversion table.

See a 17.5 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

US7¼

UK O · EU 55 · Japan 14 to 15 · India 15

17.5 mm (0.69 in) across the inside · 55.1 mm (2.17 in) around

Between US 7 and 7½? Choose 7½, 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)
6¼	M	52	16.7	52.5
6½	M½	53	16.9	53.1
6¾	N	54	17.1	53.8
7	N½	54	17.3	54.4
7¼	O	55	17.5	55.1
7½	O½	56	17.7	55.7
7¾	P	56	17.9	56.3
8	P½	57	18.1	57.0
8¼	Q	58	18.3	57.6

Your questions on a 17.5 mm ring

How long is the inside of a 17.5 mm ring, measured all the way round?

Round the inside it is 55.0 mm, which is 5.5 cm. Straight across, it is 0.69 inches.

Which US ring size matches 17.5 mm across?

It is close to a US 7¼. In the UK that ring is O, and in Europe 55.