Understanding Your Blood Oxygen (SpO₂) Data

Blood oxygen (SpO₂) shows how well oxygen is being carried around your body in your blood. Here's what your readings mean and how to use them.

⚠️ If you feel unwell: If you have shortness of breath, chest pain, confusion, bluish lips or face, or feel very unwell, contact a medical professional or emergency services straight away, whatever your band says.

What Is SpO₂?

SpO₂ stands for peripheral oxygen saturation. It measures the percentage of the haemoglobin in your blood (the protein that carries oxygen) that's carrying oxygen.

For example, a reading of 98% means 98% of your haemoglobin is carrying oxygen, which is typical for most healthy people at rest.

How Your Band Measures SpO₂

The optical sensors on the back of your band shine light into your skin. Blood that's carrying oxygen absorbs light differently from blood that isn't, and your band uses this difference to estimate your blood oxygen level.

No blood oxygen data? Readings are taken automatically at regular intervals once blood oxygen monitoring is switched on in the QWatch Pro app. For a reading right now, use One Key Measurement.

Where to Find Your SpO₂ Data

Open the QWatch Pro app and go to the Blood Oxygen section.

Apple Health: Blood oxygen readings stay in the QWatch Pro app. They don't currently sync to Apple Health.

SpO₂ Reference Ranges

The app uses these general reference ranges:

• Low (below 95%): below the typical resting range
• Normal (95–97%): typical oxygen levels
• Optimal (98% and above): strong oxygen levels

For most people, readings between 95% and 100% are normal, and small changes from day to day don't need any action.

What If My Reading Is Low?

A single low reading is often caused by movement, a loose fit or cold hands. Adjust your band, sit still and take a One Key Measurement.

If your readings are still low, check them with a pulse oximeter (a fingertip device designed for this). As a general guide from the NHS:

• 94% or lower: speak to a healthcare professional for advice
• 92% or lower: seek urgent medical help

What Affects Your SpO₂ Readings?

Short-term changes in blood oxygen are normal. Your readings can also be affected by:

• Sleep position: lying on your arm or wrist can briefly restrict blood flow
• Cold hands: cold skin reduces blood flow and can affect the reading
• Breathing: shallow breathing can briefly lower your blood oxygen
• Altitude: blood oxygen naturally drops at higher altitudes
• Movement: moving during a reading makes it less accurate
• Band fit: a loose band reduces the sensor's contact with your skin
• Skin tone and tattoos: light-based oxygen readings can be less accurate on darker skin, and may show higher readings than your actual level. Tattoos under the sensor can also affect readings.

How to Use Your SpO₂ Data

Like all your band's metrics, blood oxygen is most useful as a trend over time rather than a single reading.

Things to look out for:

• Readings that stay below 95% while resting. It's worth speaking to a healthcare professional about this.
• Frequent drops in blood oxygen while you sleep. It's worth mentioning these to your doctor.
• Changes at high altitude, if you travel to high places

Getting the Most Accurate Readings

• Wear your band about one finger-width above your wrist bone, with the sensor flat against your skin
• Sit still during One Key Measurements
• Make sure your hands are warm
• Keep the sensor clean and free of lotion

See How to Wear Your Band Correctly for more.

Important

Your band's blood oxygen readings are estimates designed for general wellness tracking. They aren't a replacement for a medical pulse oximeter, can't diagnose any condition, and shouldn't be used to make medical decisions. If you have breathing concerns or your readings are regularly low, speak to a qualified healthcare professional.

Still have questions? Email us at info@hlthtrack.com.