Blood Oxygen Level (SpO2) – What You Should Know

Blood Oxygen Level (SpO2) – What You Should Know

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Red blood cells coursing through a vein.

Wondering what your blood oxygen saturation level is—and how you can measure it? Let's go through a series of basic Q&As about this vital sign.

What is pulse oximetry?

molecule haemoglobin. Each haemoglobin molecule can bind with 4 oxygen molecules. Vector diagram.

Pulse oximetry is a noninvasive method that enables the measurement of a person’s blood oxygen saturation, which is often referred to as SpO2 or “The Fifth Vital Sign” (the first 4 being your pulse, temperature, blood pressure and respiratory rate).


What is SpO2, a.k.a. blood oxygen saturation?

It is a percentage that reflects the level of oxygen available in your blood.

Why do doctors use it?

Pulse oximetry is a method doctors use for rapid assessment and monitoring of a patient’s respiratory function. It is also used to determine which patients might be suffering from hypoxia and should take additional tests.

"Everybody can benefit from tracking their SpO2 themselves"

Self-tracking your blood oxygen level?

Until recently doctors were the only ones to use pulse oximeters, generally in a clinical setting. But as these tools are now more common (understand “smaller and cheaper”) self-tracking your SpO2 has become a reality.

In fact, everybody can benefit from tracking their SpO2 themselves. Being a healthy young man or woman doesn’t mean that you won’t benefit from a preventive tracking of respiratory problems—checking your blood oxygenation can provide you with an early warning sign (plus you’ll have a history of measurements to show your doctor, which they are likely to welcome).

If you are a mountain climber or an athlete training in high altitude to boost your endurance, measuring your blood oxygen saturation is very relevant as it can bring to light potentially life-threatening hypoxic conditions. This easy-to-use method is also great for people affected by a wide variety of chronic illnesses, including asthma and COPD (Chronic Obstructive Pulmonary Disease) as it helps them quickly assess the severity of their condition.

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How should SPO2 readings be interpreted?

Your SpO2 is considered to be normal when it is above 95%. If it is around or under 92% your blood contains an abnormally low level of oxygen, and we recommend you talk about it with your doctor.

When should I measure my SpO2?

You can measure your blood oxygen level at rest, during, or after physical activities.

That's it!

Hopefully this list of SpO2-related frequently asked questions quenched your thirst for knowledge about your Blood Oxygen Level!


At Withings, we make a range of products that empower people to make the right decisions for their health. Our award-winning connected devices are known for personalization, cutting-edge design, and ease of use, allowing anyone to measure, monitor, and track what matters via seamless connection to the free Health Mate app available for iOS & Android.
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