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Ring size 4½ in mm and international sizes

A US/Canadian size 4½ ring is 15.3 mm across the inside and 48.0 mm around. This is on the smaller side of adult sizes and common for little fingers, slim fingers and midi rings.

3456789101112134½
US / Canada
4½
UK / Australia
I½
EU / ISO
48
Japan / China
8
India
8
Italy / Spain / CH
8
Inside diameter
15.3 mm
Circumference
48.0 mm
Diameter (in)
0.602″

Size 4½ and its neighbours

USUKEUJapanDiameterCircumference
4H½47714.88 mm46.8 mm
4¼I47815.08 mm47.4 mm
4½I½48815.29 mm48.0 mm
4¾J49815.49 mm48.7 mm
5J½49915.69 mm49.3 mm

Check it's really your size

A strip of paper wrapped around your finger should measure 47–49 mm for a size 4½. If you're buying a band 6 mm or wider, consider size 5 instead. Not sure? Try the ring size calculator or the online sizer.

Questions people ask

What is ring size 4½ in mm?

A US size 4½ ring has an inside diameter of 15.3 mm (0.602 in) and an inside circumference of 48.0 mm.

What is a US 4½ in UK and European sizes?

US 4½ is UK/Australian I½ and EU (ISO) 48. In Italy, Spain and Switzerland it is 8.

What is a US 4½ in Japanese sizes?

The nearest Japanese and Chinese size is 8.

How do I know if I'm a size 4½?

Wrap a paper strip around your finger: if it measures about 48 mm, you're a 4½. Or measure a ring that fits: about 15.3 mm across the inside.