Buying guide
Ring size guide
Sizing matters most on engagement and eternity rings, where a diamond-set band is hard, or impossible, to resize after the fact. Here is how to measure, how the systems line up, and what can be adjusted later.
How to measure
- Measure an existing ring. Take a ring that already fits the right finger and measure the inside diameter in millimetres, then match it to the table below.
- Or size on a mandrel. A professional finger gauge and mandrel is the most reliable read, especially before a made-to-order piece.
- Measure warm, at the end of the day. Fingers are smallest when cold and in the morning, so an early or cold measurement reads too small.
Size conversions
Approximate equivalents by inside diameter. Diameter is the constant across systems, so it is the safest figure to confirm.
| US | UK | EU | Diameter (mm) |
|---|---|---|---|
| 4 | H½ | 47 | 14.9 |
| 5 | J½ | 49 | 15.7 |
| 6 | L½ | 52 | 16.5 |
| 7 | N½ | 54 | 17.3 |
| 8 | P½ | 57 | 18.2 |
| 9 | R½ | 60 | 19.0 |
| 10 | T½ | 62 | 19.8 |
What can be resized, and what cannot
The band decides how much room there is later. A solitaire or half band with a plain shank usually moves a size or two. A full eternity or full-pavé band, set all the way round, has no plain metal to work, so it is made to a confirmed size rather than resized. Wide and heavily set bands also fit more snugly, so size up a quarter to a half for these, and a knuckle larger than the base of the finger may need a touch more room to pass over.
This is why Kiran confirms finger size in millimetre diameter before a made-to-order or eternity piece goes into production. See the diamond shapes guide for how a stone sits in a setting, or request trade access to order at your account pricing.
Common questions
Can an eternity ring be resized?
Rarely. A full eternity or full-pavé band is set with stones all the way round, so there is no plain metal to cut and rejoin. These are made to a confirmed finger size. A half band or a solitaire with a plain shank can usually move one to two sizes.
How much can a diamond band be resized?
Most plain-shank rings move a size or two either way without disturbing the setting. Beyond that the shank thins or the head geometry shifts. Platinum and gold resize well; pieces set close to the shank, or in less workable metals, are more limited.
What is the most reliable way to size a finger?
Measure an existing ring that fits the right finger by its inside diameter, or have the finger sized on a professional mandrel. Paper-strip methods are a rough guide only. Measure warm and late in the day, when fingers sit at their largest.
US or European sizing for a made-to-order ring?
Confirm the size in millimetre inside diameter alongside the local size. Diameter is unambiguous across systems, which removes conversion error on a made-to-order piece that cannot easily be adjusted afterwards.
