Ring size

Ring size 3.5: US 3.5 in mm, UK, EU and Japan

A US size 3.5 ring has an inside diameter of 14.5 mm and an inside circumference of 45.5 mm. The same ring is a G½ in the UK and Australia, a 45.5 on the EU/ISO scale and a 5 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 3.5 in every sizing system

US 3.5 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 3F½44.2414.1
US 3.5This sizeG½45.5514.5
US 4H½46.8714.9

What a size 3.5 ring measures

Inside diameter 14.5 mm (about 0.57 in), inside circumference 45.5 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 3.5 a common ring size?

US 3.5 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 3.5 in mm?

US 3.5 is 14.5 mm across the inside and 45.5 mm around the inside. The millimeter circumference is also the EU/ISO size, 45.5.

What is US 3.5 in UK ring sizes?

US 3.5 is a UK and Australian G½. UK letters step 1.25 mm of circumference at a time, so a half letter is a real difference.

What is US 3.5 in EU ring sizes?

US 3.5 is EU/ISO 45.5. The EU number is the inside circumference in millimeters, so a shop that stocks whole sizes will offer the nearest one.

What is US 3.5 in Japanese and Korean ring sizes?

US 3.5 is a Japanese and Korean 5. 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.