Ring size 4.5 in mm, cm, UK and EU

Ring size 4½ in the US means a ring 15.3 mm wide inside and 48.0 mm round. The UK calls the same ring I, Europe 48, Japan 8 and India 8.

Ring size 4.5 in every system

Ring size 4.5 in mm, cm, UK and EU: every system
US and Canada	4½
UK, Ireland, Australia	I
Europe (EU)	48
Japan and China	8
India	8
Italy, Spain, Switzerland	8
Across the inside	15.3 mm · 1.53 cm · 0.602 in
Around the inside	48.0 mm · 4.8 cm · 1.89 in

One whole size bigger, US 5½, is just under 1 mm wider. All of these numbers are from the standard ring size conversion table.

Check a ring against ring size 4.5 on your screen

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

US4½

UK I · EU 48 · Japan 8 · India 8

15.3 mm (0.60 in) across the inside · 48.0 mm (1.89 in) around

For a wide band (over 4 mm), go up about half a size, to US 5.

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)
3½	G	46	14.5	45.5
3¾	G½	46	14.7	46.1
4	H	47	14.9	46.8
4¼	H½	47	15.1	47.4
4½	I	48	15.3	48.0
4¾	J	49	15.5	48.7
5	J½	49	15.7	49.3
5¼	K	50	15.9	50.0
5½	K½	51	16.1	50.6

Common questions about ring size 4.5

How many millimetres is US ring size 4½?

It is 15.3 mm wide inside and 48.0 mm round the inside. In inches, the width is 0.60.

How many centimetres is US ring size 4½?

Round the inside it is 4.8 cm, and it is 1.53 cm wide.