Your results may vary depending on the type of test used to measure your blood oxygen levels.
A pulse oximeter reading indicates what percentage of your blood is saturated, known as the SpO2 level. A typical, healthy reading is 95–100%Trusted Source. If your SpO2 level is less than 92%, a doctor may recommend you get an ABG.
A pulse ox is the most common type of test because it’s noninvasive and provides quick readings. However, FDA-approved pulse oximeters may have a 2–3%Trusted Source error window when compared with ABG values.
An ABG measurement will determine the partial pressure of oxygen in your blood, known as PaO2. A normal ABG oxygen level for healthy lungs is between 75 and 100Trusted Source millimeters of mercury (mm Hg).
This test is very accurate but more invasive.
People who smoke may also need an ABG test as they might have an inaccurately high pulse ox reading. Smoking causes carbon monoxide to build up in your blood. A pulse ox can’t tell the difference between this type of gas and oxygen.
Arterial blood gas (ABG) Pulse oximeter
Healthy level 75–100 mm Hg 95–100%
When to get medical help less than 74 mm Hg less than 95%
These ranges may differ for people with COPD or other lung diseases. If you are living with a lung condition, discuss your levels with your doctor. They can help you identify what a normal range will look like for you.