Ring size

Ring size 3: US 3 in mm, UK, EU and Japan

A US size 3 ring has an inside diameter of 14.1 mm and an inside circumference of 44.2 mm. The same ring is a F½ in the UK and Australia, a 44.2 on the EU/ISO scale and a 4 in Japan and Korea. The figures below come from the same geometry as the full chart, so they agree with it to a tenth of a millimeter.

US 3 in every sizing system

US 3 with the half size below and above it, so a measurement that lands between two sizes still has a row to read.
US / CanadaUK / AustraliaEU / ISO (circumference, mm)Japan / KoreaInside diameter (mm)
US 3This sizeF½44.2414.1
US 3.5G½45.5514.5

What a size 3 ring measures

Inside diameter 14.1 mm (about 0.56 in), inside circumference 44.2 mm. Measuring a ring that already fits? Measure the inside edge to edge for the diameter. Measuring a finger? Wrap a strip of paper around its base and compare the overlap with the circumference.

Is US 3 a common ring size?

US 3 is below the 4.5 to 7.5 range most women's engagement rings are stocked in. Many designs can be made or resized down to it, but ask before ordering a setting with stones around the band.

Between two sizes?

Take the larger one. A ring is easier to make smaller than larger, a wide band needs a little more room than a thin one, and fingers swell in heat and in the evening. A jeweler's sizer set settles it in a minute.

Convert a measurement to a ring size

Measure a ring that already fits the right finger, or the finger itself, and enter the number in millimeters.

What did you measure?

Quick answers

Frequently asked questions

What is a US ring size 3 in mm?

US 3 is 14.1 mm across the inside and 44.2 mm around the inside. The millimeter circumference is also the EU/ISO size, 44.2.

What is US 3 in UK ring sizes?

US 3 is a UK and Australian F½. UK letters step 1.25 mm of circumference at a time, so a half letter is a real difference.

What is US 3 in EU ring sizes?

US 3 is EU/ISO 44.2. The EU number is the inside circumference in millimeters, so a shop that stocks whole sizes will offer the nearest one.

What is US 3 in Japanese and Korean ring sizes?

US 3 is a Japanese and Korean 4. Those scales step a third of a millimeter of diameter per number, so they are finer than US half sizes.

Every ring size, US 3 to 13

Conversions are rounded to the nearest standard size, and published charts differ from each other by up to half a size. Treat the result as a close estimate, confirm it with a jeweler's sizer before buying, and check the resizing policy.