Pulse ox accuracy

I did compare it with a medical device and had the same issue as most of you, Mine is always 4-6% less than the medical grade device. Same thing happen with all the members of my family, a did put it in all 5 of them just to check, there has to be something a bit off with this device. One curious fact, everytime I go out and do anything outside, somehow it does measure within the same range as the medical device.

i think Garmin have to think about a calibration option, so you can enter the measurement of the medical device and the onboard sensor use this difference to correct the measurement, my readings are mostly 4-6% lower as on a medical device too

I have my watch to measure only while asleep. I do spend more time on my back sleeping, although I do occasionally sleep on my watch side. 

Out of 22 averaged samples, my average SpO2 was 95.86% +/- 0.33%.

I was in A&E today and had my blood O2 measured three times on different hospital monitors. Each time it exactly matched the watch reading. I was very surprised. Your percentage may vary etc ...

Update, I’ve been back to outpatient clinic and done the comparison with two more hospital monitors. Again, exactly matches my watch reading both times. Again, surprised. Yes, sample of one watch here. I don’t wear it especially tight.  

definitely this is not accurate and useless!

Thanks! This has been bothering me a bit. I feel healthy, but it's below 95% most of the time, which ought to be sign of something not good.

Same for me at night. Going to try to all day thing. I definitely sleep on my arm as I get sandwiched between my wife and the cat and contort myself to accommodate both.