Pulse Oximeters and Skin Tone: The Research

Pulse oximeters can read higher than the true value on darker skin. That's a published finding, and regulators have acted on it. Here's what's known and what you can do about it.

Why would skin tone matter?

An oximeter shines light through your finger and measures what comes out the other side. Melanin, the pigment in skin, absorbs some of that light too. If a device was calibrated mostly on people with lighter skin, its estimate can be off for everyone else.

What did the studies find?

The best known one was published in the New England Journal of Medicine in 2020. It compared oximeter readings with blood samples in hospital patients.

• It looked at patients whose oximeter read 92% to 96%.
• In one hospital's data, 11.7% of Black patients in that group had a blood sample below 88%.
• For white patients it was 3.6%.

So the oximeter read too high about three times as often for Black patients. These were hospital oximeters and unwell patients, so the exact figures won't carry over to a ring worn at home.

What has the FDA said?

• February 2021. It issued a safety communication listing skin pigmentation among the things that can affect a reading, along with poor circulation, skin temperature and nail polish.
• January 2025. It published draft guidance asking makers of medical oximeters to test on at least 150 people across a wide range of skin tones.

That guidance covers oximeters sold for medical use. Consumer wellness devices aren't held to it, so check what your model's maker has published.

So is your overnight data useless?

No. The error mostly shifts the level of your readings. It matters most when you compare one number against a fixed line, like 90% or 95%.

It matters less when you compare your own nights with each other. Same finger, same device, same skin, so the offset is likely to be similar from night to night. Some studies suggest it grows at lower readings, so be more cautious with your lowest numbers.

What should you do?

• Compare your nights against each other. That's where a ring is most useful for anyone.
• Be careful with fixed lines. Your T90 and your lowest reading could look better than they are.
• Go by how you feel. If you're short of breath or exhausted, see a doctor whatever the number says.
• Tell your doctor. If you share your recordings, mention that the device may read high for you.
• Rule out the other causes. Cold hands and a loose fit affect everyone. See why your reading might be wrong.

A home oximeter isn't a sleep study on any skin tone.

If you want to compare your own nights over weeks, that's what PulseOxTracker is for.

Not a medical device. Does not diagnose, treat or prevent any condition. Discuss results and changes with a clinician.

References

1. Sjoding MW, Dickson RP, Iwashyna TJ, Gay SE, Valley TS. Racial bias in pulse oximetry measurement. New England Journal of Medicine. 2020;383:2477-2478. doi:10.1056/NEJMc2029240
2. US Food and Drug Administration. Pulse Oximeters, including a summary of the February 2021 safety communication. fda.gov. Checked October 2026.
3. US Food and Drug Administration. Pulse Oximeters for Medical Purposes - Non-Clinical and Clinical Performance Testing, Labeling, and Premarket Submission Recommendations. Draft guidance. January 2025. fda.gov