Ring size: what US, UK and EU sizes measure
A ring size is a number or letter for the inside of a band, the edge that touches the finger. A US size steps along the inner diameter: 11.63 mm at size 0, plus 0.8128 mm per size. An EU (ISO) size is the inner circumference in millimetres. A UK size is a letter, which Australia also uses.
3D Jewelry Designer1 min read
How the systems relate
A US 6 is 16.5 mm across, so its EU size, the diameter times π, is 51.9. UK letters start at A, about a US ½, and step roughly half a US size each. Conversions go through the diameter, as the ring size converter shows. Charts differ on rounding between UK letters, so confirm a letter with a ring gauge.
Measuring a size
Every system measures the inside of the shank, so band thickness never changes the size. Measure across the inside of a ring that fits for the diameter, or wrap paper round the finger for the circumference; measuring your ring size at home covers both. A wide band sits tighter than a narrow one at the same size, so a ring size chart is a starting point.
Ring size in the studio
In the ring builder, the Ring size step offers US, UK and EU sizes, and try-on sizes the ring to the one you pick. On the live camera, virtual ring try-on estimates the size with its range, since a camera cannot measure exact size. The builder, try-on and converter share one size table.
Questions
Is a ring size in millimetres the diameter or the circumference?
Either, depending on the chart. An EU size is the inner circumference, while the millimetre figure in the ring size converter is the inner diameter.
Related
- Ring Size Converter: US, UK, AU, EU and mm Chart
Convert ring sizes between US, UK and Australian letters, EU and millimetres, with a full printable chart.
- How to measure ring size at home (US, UK, AU, EU)
Two ways to measure ring size at home with a ruler, and how to turn the millimetres into a US, UK, Australian or EU ring size.
- Ring size charts for the US, UK, Australia and Europe
How US, UK, Australian and EU ring size charts measure the inside of a band, how to convert between them through the diameter, and why charts disagree.