Oura Ring Blood Oxygen (SpO2) Not Measuring — What It Means & How to Fix It

What Does This Error Mean?

SpO2 (blood oxygen) is only measured during sleep, and only when the ring stays still on your finger. A loose fit, excessive movement, or cold hands are the most common reasons for missing SpO2 data. Enable Blood Oxygen in the app settings and ensure a snug fit.

Affected Models

Oura Ring 4
Oura Ring 3
Oura Ring 3 Heritage
Oura Ring 3 Horizon

Common Causes

Blood Oxygen tracking is not enabled in the Oura app settings
Ring is not worn during sleep — SpO2 is only measured at night
Ring fits too loosely, causing signal interruptions
Excessive movement during sleep
Oura Ring 3 requires membership for SpO2 access
Nail polish or dark pigmentation on the finger near the sensor

How to Fix It

Enable Blood Oxygen monitoring in the Oura app: go to Settings > Ring Settings and toggle on 'Blood Oxygen'.

SpO2 monitoring is opt-in and off by default on some Oura Ring models. It must be explicitly enabled before the ring will measure it.
Wear the ring every night and ensure it is snug on your finger.

SpO2 is measured during sleep only. The ring needs continuous skin contact for the red and infrared LEDs to work. A loose ring breaks the signal.
If you have Ring 3, verify your Oura membership is active.

SpO2 data is a premium metric on Oura Ring 3, requiring an active monthly subscription. Ring 4 includes this feature without an ongoing membership.
Remove any nail polish from the finger you wear the ring on.

Nail polish — especially dark or glittery colors — can interfere with the optical sensor's ability to penetrate to the blood vessels below.
Warm your hands before bed if you sleep in a cold room.

Cold causes blood vessels near the skin surface to constrict, making optical SpO2 measurement less reliable. Wearing socks and keeping the bedroom above 16°C helps.

When to Call a Professional

Low blood oxygen readings (below 90%) can indicate serious conditions like sleep apnea or respiratory problems. Do not rely on the Oura Ring for medical-grade SpO2 monitoring. If you consistently feel short of breath or fatigued, see a doctor and request a clinical evaluation.

Frequently Asked Questions

What SpO2 range does Oura consider normal?

Oura considers blood oxygen readings of 95–100% as normal during sleep. Readings of 90–94% are shown as slightly low, and below 90% is flagged as a concern. Note that these are wellness-level readings, not medical-grade measurements.

Does Oura Ring detect sleep apnea?

No — Oura Ring cannot diagnose sleep apnea. It can show you SpO2 dips during sleep which might prompt a conversation with your doctor, but it is not a diagnostic tool. Sleep apnea diagnosis requires a clinical sleep study (polysomnography) or an FDA-cleared home sleep test.