Will an O2Ring Fit You? Sizing Explained
What finger sizes the Wellue O2Ring fits, how to measure yours, which finger to wear it on, and what to do if it's too loose or too tight.
The O2Ring isn't sized like jewellery. You don't pick a ring size when you order. The band is flexible and stretches to fit a range of fingers.
What sizes does it fit?
At the time of writing, Wellue's product page lists the O2Ring for finger circumferences of 55 mm to 80 mm (2.17 to 3.15 inches). That can change between hardware versions, so check the listing for the model you're buying.
Wellue has also sold a smaller version for slimmer fingers. If you're near the bottom of the range, look for it on their site.
How do you measure your finger?
- Wrap a strip of paper or a piece of string around the base of the finger.
- Mark where it overlaps.
- Lay it flat and measure it with a ruler.
Measure in the evening. Fingers are often a bit thicker at night than in the morning.
Which finger should you use?
Wellue's advice is to pick the finger that gives a snug, comfortable fit, not too tight and not too loose. So try a few.
- Slim hands: the thumb is often the best fit.
- Larger hands: try the index or middle finger.
- Either hand works. Many people prefer the one they move less in their sleep.
Once you've found a finger that works, stick with it. Then your nights are easier to compare.
How do you know it's too loose?
- It spins or slides when you shake your hand.
- Your morning recording has gaps or stretches with no reading.
A loose ring shifts when you roll over, and the sensor loses contact. See O2Ring data gaps for other causes.
And too tight?
- Your finger tingles, throbs or feels cold.
- There's a deep mark when you take it off.
Too tight restricts the blood flow the sensor reads, which also gives bad readings. Move it to a slimmer finger.
What if it just doesn't fit?
- Check the seller's returns policy before you order.
- Look at the SleepU or Checkme O2 Max. They use a soft finger sensor on a short cable, which suits fingers outside the ring's range.
We compared all three in O2Ring vs Checkme O2 Max vs SleepU.
Got one that fits? Your first night with an O2Ring covers what to do next. After a week or two, PulseOxTracker lets you compare those nights side by side.
Not a medical device. Does not diagnose, treat or prevent any condition. Discuss results and changes with a clinician.