Commissions
How to measure ring size accurately at home
A five-minute method using thread or an existing ring, the mistakes that throw the measurement off, and how to size a partner's finger without giving away the surprise.
Incorrect sizing is the single most common reason a commission comes back to the bench. A plain band is easy to adjust. A ring set with stones all the way round, or with a continuous pattern, distorts when it is stretched or cut down — some designs have to be remade entirely.
The method below takes five minutes and is accurate enough for most work.
Gather what you need
A length of thread or a strip of paper about 15 cm long and no more than 5 mm wide, a ruler marked in millimetres, and a pen.
Do not use elastic or a rubber band. It stretches as you wrap and gives a reading that is too large.
Measure in the evening
Fingers change size through the day. They are smallest in the morning and largest in the late afternoon and evening, as circulation and temperature rise.
Measure in the evening with hands at normal temperature. Do not measure straight after exercise or in cold weather — either can shift the reading by half a size.
Wrap and mark
Wrap the thread around the base of the finger where the ring will actually sit. Snug enough to rotate, loose enough not to bite.
Mark the point where the end overlaps, then unwrap and measure from the end to the mark. That length is the finger circumference in millimetres.
Repeat three times and take the middle value. If the three readings vary by more than 1 mm, your wrapping tension is inconsistent — start again.
Check the knuckle clears
The step people forget: the ring has to pass over the knuckle. If the knuckle is noticeably larger than the base of the finger, measure it too and use the larger figure.
If the difference exceeds 2 mm, tell your jeweller. We can fit small beads inside the shank so the ring clears the knuckle but does not spin once it is on.
Convert to a size
| Circumference (mm) | Thai size | US size |
|---|---|---|
| 47.8 | 8 | 4.5 |
| 49.3 | 9 | 5 |
| 50.6 | 10 | 5.5 |
| 51.9 | 11 | 6 |
| 53.1 | 12 | 6.5 |
| 54.4 | 13 | 7 |
| 55.7 | 14 | 7.5 |
| 57.0 | 15 | 8 |
| 58.3 | 16 | 8.5 |
| 59.5 | 17 | 9 |
If your measurement falls between two sizes, take the larger one. Reducing a ring is easier than stretching it.
Sizing a surprise proposal
The most reliable approach is to borrow a ring they already wear for one evening and measure its internal diameter with a ruler, or press it into a bar of soap and photograph the impression for us.
Check which finger the borrowed ring is worn on. The ring finger of the non-dominant hand is typically about half a size smaller than the dominant one.
If there is genuinely no way to find out, the common averages are Thai 12-13 (US 6.5-7) for women and Thai 18-20 (US 8.5-9.5) for men. Propose with an approximate size and adjust afterwards — we resize free once within six months.
Do wide bands need a different size
Yes. Anything over 6 mm wide feels tighter than a slim band at the same nominal size. Allow half to a full size extra, and tell us the intended width when you order so we can advise.
Can an eternity ring be resized
Only marginally, usually no more than half a size, because cutting the shank runs into the stone settings. Beyond that the piece generally has to be remade, so accurate sizing matters far more for these designs.
Is measuring an existing ring more accurate than measuring the finger
It is, provided that ring is worn on the same finger and genuinely fits, since it removes the variable of wrapping tension. If the existing ring is loose or tight, measuring the finger directly gives a better result.