One circle of light, measured in many languages.
A ring size seems like a simple number until you cross a border. The same ring might be a 7 in New York, an N½ in London, around 54 in much of Europe and something else again in Tokyo. None of these systems is wrong; each grew up in its own place, describing the same circle in its own way. If you are ordering from Aetheris, where rings are sized in US sizes, understanding how the systems relate will help you choose with confidence.
Why every system counts differently
- The United States and Canada use numbers, with half sizes in between; each whole size adds roughly 2.5 millimeters to the inside circumference.
- The United Kingdom, Ireland and Australia use letters, with half letters in between, so about two letters pass for every whole US size.
- Much of continental Europe describes a ring by its inside circumference in millimeters, so the number itself is close to a measurement.
- Japan uses its own numbered scale, which climbs in finer steps than whole US sizes, so its numbers never line up neatly with American ones.
Because the steps are different sizes, simply matching labels from one list to another can lead you astray. A good chart solves this by anchoring every system to the same physical measurement. And since UK and Australian charts share the same letters, a size from either country converts in exactly the same way.
Millimeters: the measurement every chart shares
The most reliable way to move between systems is to set the labels aside and work in millimeters. Two measurements are useful. Inside circumference is the distance around the inside of a ring, or around your finger. Inside diameter is the distance straight across the inside of a ring, from edge to edge. They are linked by a constant: circumference equals diameter multiplied by pi, roughly 3.14. Know either figure and you can find your place on any chart, including our international ring size guide, which lists US, UK, European and Japanese sizes side by side.
A few reference points
For orientation, here is how the whole sizes in the Aetheris range compare. Half sizes sit between each row, and the full guide shows every one of them.
| US size | Inside circumference | Inside diameter | UK and Australia |
|---|---|---|---|
| 5 | 49.3 mm | 15.7 mm | J½ |
| 6 | 51.9 mm | 16.5 mm | L½ |
| 7 | 54.4 mm | 17.3 mm | N½ |
| 8 | 57.0 mm | 18.1 mm | P½ |
| 9 | 59.5 mm | 18.9 mm | R½ |
| 10 | 62.1 mm | 19.8 mm | T½ |
Notice how small the steps are. A whole US size is less than a millimeter of inside diameter, and a half size roughly 0.4 millimeters, which is why careful measuring matters more than a quick guess.
Converting your size, step by step
- Measure in millimeters: either the inside diameter of a ring that already fits the intended finger, or the circumference of the finger itself. Our guide to finding your ring size at home explains both methods.
- Find the closest millimeter value on the conversion chart, rather than translating a label from one system to another.
- Read across to the US column to find the matching size.
- If you fall between two sizes, consider the band: wider bands tend to feel snugger than slim ones, and a larger knuckle may call for the size above.
Measure more than once, ideally at different times of day. Fingers are often slightly larger in warm weather and later in the day, and slightly smaller when cold.
A few common slips are worth avoiding. The most frequent is mixing up diameter and circumference: a figure near 17 mm is almost certainly a diameter, while one near 54 mm is a circumference, and reading one as the other points to a very different size. String that stretches, or thick paper, can add a fraction of a millimeter, which is enough to shift a half size. And a ring borrowed from a different finger, or from the other hand, describes that finger rather than the one you have in mind.
Sizing at Aetheris
Rings in the collection are offered from US 5 through US 10 in half-size steps, and each one is made to order in whichever size you select. Size menus can vary slightly between designs, so check the options on the product page itself; the Starlight Four-Prong Ring, for example, offers every half size from 5 to 10. Since each ring is created after you order it, and a change of mind is not a reason for a return or refund, confirm your size before you choose. If your measurement falls outside the range, or you are unsure how a conversion applies, email aetheristechhk@gmail.com before ordering.
Ready to choose
With your size translated into millimeters and matched to a US number, the rest is the pleasant part. Browse the Vow & Eternal ring collection, compare silhouettes in our diamond shapes guide, and find the circle of light that fits.