How SpO2 Oxygen Sensor Work In Smartwatch

By: Rahul Makwana

To put it simply, When you measure the SpO2 on a smartwatch, it projects LED lights into the skin to measure oxygen levels, the difference between injected light and reflected light is the final result of SpO2 in blood cells.

Most of  the budget smartwatches uses the optical heart rate sensor to measure the heart rate as well as the SpO2 level in our blood

Is SpO2 Sensor Reliable In Smartwatch?


First let's see how Oximeter works, so it will be easy for you to see whether the SpO2 sensor on watch is reliable or not?

When you place your finger in an oximeter, one end of the device emits light using a light source, which then passes through the finger and then hits the sensors at the other end.

The closer the sensor is to your skin is better as it can pass through the light into your body.

Which means, oximeter measures the SpO2 better because it hits hard on your finger.

In simple words, No SpO2 Sensor in smartwatches are not reliable, still, in the end, it also depends on what kind of smartwatch you’re using,

For example, measuring SpO2 on Apple Watch or Galaxy Watch will be more reliable as they use good quality SpO2 sensors whereas using a SpO2 sensor in a Rs 5000 smartwatch won’t give you an accurate result.

What is SpO2 or Blood Oxygen


The SpO2 or blood oxygen levels are the percentage of oxygen in the blood. Simply put, it measures how much oxygen your red blood cells carry.

Also, if you’re having symptoms like headache, shortness of breath, coughing, sneezing, bluish color in skin or nails, and more.

In this case, you better visit a nearby hospital because Lower blood oxygen levels can result in Hypoxemia.

According to WHO, a patient with oxygen saturation of 94% or lower needs quick medical attention. And if less than 90%, it’s a clinical emergency.