Size 45 ring in US and UK sizes

Size 45 ring, as Europe counts it, means 45 mm round the inside, or 14.3 mm wide. In the US it is about a 3¼, and in the UK F½.

Size 45 ring in every system

Size 45 ring in US and UK sizes: every system
US and Canada	about 3¼
UK, Ireland, Australia	F½
Europe (EU)	45
Japan and China	5
India	5
Italy, Spain, Switzerland	5
Across the inside	14.3 mm · 1.43 cm · 0.564 in
Around the inside	45.0 mm · 4.5 cm · 1.77 in

Each European size is 1 mm bigger round than the one before, and 45 mm is the same as 4.5 cm. All of these numbers are from the standard ring size conversion table.

Check a ring against a size 45 ring 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

US3¼

UK F½ · EU 45 · Japan 5 · India 5

14.3 mm (0.56 in) across the inside · 44.8 mm (1.76 in) around

Between US 3 and 3½? Choose 3½, 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)
2¼	D½	42	13.5	42.3
2½	E	43	13.7	42.9
2¾	E½	44	13.9	43.6
3	F	44	14.1	44.2
3¼	F½	45	14.3	44.8
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

Common questions about a size 45 ring

How many millimetres is a size 45 ring?

It is 14.3 mm wide inside and 45.0 mm round the inside. In inches, the width is 0.56.

How many centimetres is a size 45 ring?

Round the inside it is 4.5 cm, and it is 1.43 cm wide.