UK ring size K in US sizes and mm

UK ring size K is 50.0 mm round the inside and 15.9 mm wide. The US calls it about a 5¼, and Europe 50.

UK ring size K in every system

UK ring size K in US sizes and mm: every system
US and Canada	about 5¼
UK, Ireland, Australia	K
Europe (EU)	50
Japan and China	9 to 10
India	10
Italy, Spain, Switzerland	10
Across the inside	15.9 mm · 1.59 cm · 0.627 in
Around the inside	50.0 mm · 5.0 cm · 1.97 in

Going up one UK letter adds a little over 1 mm round the inside. Ireland, Australia and New Zealand share these letters. All of these numbers are from the standard ring size conversion table.

Check a ring against UK ring size K 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

US5¼

UK K · EU 50 · Japan 9 to 10 · India 10

15.9 mm (0.63 in) across the inside · 50.0 mm (1.97 in) around

Between US 5 and 5½? Choose 5½, 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)
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
5¾	L	51	16.3	51.2
6	L½	52	16.5	51.9
6¼	M	52	16.7	52.5

Common questions about UK ring size K

How many millimetres is UK ring size K?

It is 15.9 mm wide inside and 50.0 mm round the inside. In inches, the width is 0.63.

How many centimetres is UK ring size K?

Round the inside it is 5.0 cm, and it is 1.59 cm wide.