Blood oxygen levels refer to the amount of oxygen circulating in the blood. Normal blood oxygen levels fall between 75 and 100 millimeters of mercury (mm Hg) on arterial blood gas (ABG) test results.

Pulse oximeters use light to measure how much oxygen is in a person’s blood. For most people, a normal pulse oximeter reading is between 95% and 100%, researchers said in background notes. Readings ...