Buying a smart ring feels straightforward until you reach the sizing question. Unlike a watch, you cannot tighten a band after delivery, so getting the fit right before ordering matters.
The good news is that you can measure your finger at home in a few minutes. Below are two simple methods and a US size 6–13 chart for choosing your Ruely Smart Ring.
Why smart ring fit matters
A consistent, comfortable fit helps the ring stay in contact with your skin throughout the day and night. If it is too loose, it may rotate or slide. If it is too tight, it can become uncomfortable as your fingers naturally change size during the day.
A good fit should feel snug without squeezing. You should be able to remove the ring with gentle resistance over the knuckle.
Method 1: Measure with a paper strip
- Prepare the tools. Cut a strip of paper about 10 cm long and have a pen and a ruler ready. Non-stretch string can also work, but paper is usually easier to keep flat.
- Wrap the exact finger. Place the paper around the base of the finger where you plan to wear the ring. Keep it snug but do not pull it tight. Mark the point where the paper overlaps.
- Measure the circumference. Lay the strip flat and measure from the starting edge to your mark in millimetres. Compare that number with the circumference column in the chart below.
Method 2: Measure a ring you already own
Choose a ring that fits the same finger comfortably. Place it flat on a ruler and measure straight across the widest part of the inside opening, from one inner edge to the other. Do not include the thickness of the ring itself. Compare this measurement with the inner-diameter column below.
Smart ring size chart: US 6–13
| US size | Finger circumference | Inner diameter |
|---|---|---|
| 6 | 51.9 mm | 16.5 mm |
| 7 | 54.4 mm | 17.3 mm |
| 8 | 57.0 mm | 18.1 mm |
| 9 | 59.5 mm | 18.9 mm |
| 10 | 62.1 mm | 19.8 mm |
| 11 | 64.6 mm | 20.6 mm |
| 12 | 67.2 mm | 21.4 mm |
| 13 | 69.7 mm | 22.2 mm |
If your measurement falls between two sizes, measure again later in the day, when fingers may be slightly larger. Choose the size that stays in place without creating pressure; do not assume that an intentionally loose fit will work equally well.
Which finger should you measure?
Finger size can differ between hands and even between neighbouring fingers. Measure the exact finger and hand where you plan to wear the ring. The index and middle fingers are common choices, but comfort and consistent contact matter more than following a single rule.
Common measuring mistakes
- Measuring only once: temperature, activity and time of day can change finger size.
- Pulling the paper too tight: the strip should touch the skin without compressing it.
- Ignoring the knuckle: make sure the chosen size can pass over your knuckle with gentle resistance.
- Using stretchy material: elastic string can produce a smaller and inaccurate measurement.
- Measuring the wrong finger: always size the finger on which you intend to wear the ring.
A quick fit check
When your ring arrives, check that it stays in place during normal movement, feels comfortable when you make a fist, and comes off with gentle resistance. It should not leave deep marks or feel painful.
Ready to choose your size?
Once you have matched your measurement to the chart, explore the Ruely Smart Ring, available in Pink, Black and White in US sizes 6–13. Review sleep, activity and everyday patterns in Qring without a monthly subscription.
Ruely Smart Ring provides lifestyle information and is not intended to diagnose, treat, cure or prevent any medical condition.