The Smart Ring Lab

RingConn Gen 3 sizing guide: new sizing system, don't assume your Gen 2 size

2026-05-07 · 3 min read

Important: RingConn Gen 3 uses a different sizing system than Gen 2.

If you wear size 10 in Gen 2, size 10 in Gen 3 may not fit the same. This is the most common mistake new buyers make.

Why the sizing system changed

RingConn redesigned the internal sensor layout for Gen 3. The ring shape is slightly different, and the sizing calibration was updated to match.

This means:

  • Gen 2 sizing kit won’t work for Gen 3
  • Your Gen 2 ring size is not a reliable reference
  • You need to order a new sizing kit

How to get the right size

Step 1: Order the free sizing kit

RingConn offers a free sizing kit when you order Gen 3. Don’t skip this step.

The kit contains plastic sizing rings in multiple sizes. You wear them for 24-48 hours to find the best fit.

Step 2: Wear the sizing rings during normal activity

Don’t just try them on for 5 minutes. Wear them:

  • During sleep (this is when the real ring will be worn most)
  • During typical daily activities
  • On the finger you plan to use

Step 3: Check for two things

  1. Comfort: Can you sleep with it? Does it bother you during normal hand use?
  2. Fit stability: Does it rotate or shift when you move your hand?

A slightly loose ring causes sensor accuracy problems. A slightly tight ring causes discomfort. Aim for the middle ground.

Which finger to use

RingConn recommends:

  • Index finger (most common)
  • Middle finger (alternative if index doesn’t fit well)

Avoid:

  • Ring finger (too much movement during daily activities)
  • Thumb (unusual shape, poor sensor contact)

Common sizing mistakes

Mistake 1: Guessing based on Gen 2

“I wore size 10 in Gen 2, so I’ll order size 10 in Gen 3.”

This is the #1 cause of returns. The sizing systems don’t match.

Mistake 2: Measuring with string or tape

String and tape measurements are not accurate enough. The sizing kit is free. Use it.

**Mistake 3: Ordering too tight because “I want secure fit”

A tight ring causes:

  • Discomfort during sleep
  • Skin irritation
  • Finger swelling in hot weather

A slightly loose ring is better than a tight ring. The sensors need skin contact, but they don’t need compression.

Mistake 4: Ordering too loose because “I want comfort”

A loose ring causes:

  • Sensor rotation (reads different spots)
  • Ambient light leakage
  • Inconsistent data

The ring should stay in place when you move your hand normally.

Trade-in sizing

If you’re upgrading from Gen 2, RingConn offers up trade-in discount (up to $70). But you still need the new sizing kit.

Don’t assume your trade-in ring will fit the same as your old one.

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