Ring sizing is the measurement people get wrong most often. A ring that spins on your finger and a ring you cannot get past your knuckle are the same mistake made in opposite directions, and both usually come from measuring once, in the morning, on a cold day.
Why the time of day matters
Fingers change size. They are smallest first thing in the morning, smallest again in cold weather, and largest at the end of a warm day or after exercise. The swing between a cold morning and a warm evening is often a full half size, sometimes more.
Measure at the end of the day, at room temperature, with warm hands. That gives you a size that works most of the time rather than one that only works at 7am in February.
The paper strip method
You need a strip of paper about 3mm wide, a pen and a ruler with millimetres.
- Wrap the strip around the base of the finger you want the ring to sit on. Snug, not tight — it should not dent the skin.
- Now slide the loop over your knuckle without loosening it. This is the step people skip, and it is the one that matters. The ring has to pass the knuckle, so the knuckle sets the minimum.
- If it will not pass the knuckle, loosen it slightly until it does, and use that as your measurement.
- Mark where the paper overlaps, lay it flat and measure to the mark in millimetres. That number is your finger circumference.
Circumference to US ring size
| US size | Circumference (mm) | Inside diameter (mm) |
|---|---|---|
| 5 | 49.3 | 15.7 |
| 5.5 | 50.6 | 16.1 |
| 6 | 51.9 | 16.5 |
| 6.5 | 53.1 | 16.9 |
| 7 | 54.4 | 17.3 |
| 7.5 | 55.7 | 17.7 |
| 8 | 57.0 | 18.1 |
| 8.5 | 58.3 | 18.5 |
| 9 | 59.5 | 19.0 |
| 9.5 | 60.8 | 19.4 |
| 10 | 62.1 | 19.8 |
Three adjustments worth making
Wide bands run small
A 2mm band and an 8mm band in the same nominal size do not feel the same. The wide one covers more of your finger and reads tighter. Go up a full size for anything 6mm or wider.
Between sizes? Go up
A slightly loose ring turns on your finger, which is mildly annoying. A slightly tight ring will not come off, which is a genuine problem — and getting a stuck ring removed is an unpleasant afternoon.
Knuckles bigger than the base
If your knuckle is much larger than the base of your finger, size to the knuckle. The ring will spin a little at rest; that is the trade for being able to put it on at all.
Measuring a ring you already own
If you have a ring that fits the right finger, measure the inside diameter across the widest point with a ruler and match it to the third column above. Measure the inside, not the outside — the band thickness will throw you off by half a size or more.
What not to use
Printable paper ring sizers are only accurate if your printer scaled the page to exactly 100%, and most people never check. String stretches. Tape measures are too wide and too stiff to sit flat around a finger. A narrow strip of ordinary paper beats all three.
Still unsure
Email us the product link and your measurement in millimetres and we will tell you which size to take. If it still arrives wrong, you have 30 days to return it with no restocking fee — the full detail is in our Refund & Returns Policy.
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