Finding the right ring size for a smart ring is one of the most important steps before you buy. Unlike a regular ring, a smart ring sits snugly against your skin to accurately read your biometric data — heart rate, SpO₂, skin temperature. Too loose and readings become inaccurate. Too tight and it will be uncomfortable to wear all day.
This guide will help you find your perfect Kayza ring size in minutes.
Why ring sizing matters more for smart rings
A decorative ring can be loose or tight without real consequence. A smart ring needs consistent skin contact to work correctly. The optical sensors on the inside of the ring must stay in contact with your finger for accurate heart rate and SpO₂ readings. A ring that slides around will produce inconsistent data.
Method 1: Use a string or strip of paper (recommended)
- Cut a thin strip of paper or use a piece of string about 10cm long.
- Wrap it around the finger you plan to wear the ring on. Most people choose the index finger or middle finger of their non-dominant hand.
- Mark where the paper or string overlaps to complete the circle.
- Measure the length in millimetres with a ruler. This is your finger circumference.
- Use the table below to find your Kayza ring size.
Method 2: Measure an existing ring
If you already own a ring that fits well on the intended finger:
- Place the ring on a flat surface.
- Measure the internal diameter in millimetres (the distance across the inside of the ring, not the outside).
- Use the diameter column in the size table below.
Kayza ring size chart
| Size | Inner diameter (mm) | Circumference (mm) |
|---|---|---|
| 6 | 16.5 | 51.8 |
| 7 | 17.3 | 54.4 |
| 8 | 18.2 | 57.2 |
| 9 | 18.9 | 59.3 |
| 10 | 19.8 | 62.1 |
| 11 | 20.6 | 64.7 |
| 12 | 21.4 | 67.2 |
| 13 | 22.2 | 69.7 |
| 14 | 23.0 | 72.3 |
Tips for an accurate measurement
- Measure at the end of the day — fingers swell slightly in warm weather and after activity. The UAE climate means this matters more than most places.
- Measure the dominant knuckle — the ring needs to pass over your knuckle to get on and off. Measure both the base of the finger and the knuckle; if they differ, size up.
- If you’re between sizes, size up — a slightly looser fit is more comfortable and can be adjusted with a ring size adjuster.
- Avoid measuring in the morning — fingers are at their narrowest after sleep.
Still not sure? Contact us
If you're unsure which size to order, email us at customerservices@kayza-mena.store and our team will help. We're based in the UAE and respond within 24 hours.
Ready to order? Shop the Kayza Ceramic Smart Ring — available in sizes 7 to 13.