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Understanding Normal Blood Oxygen Level

When you breathe, oxygen from the ambient air travels through your nose, down your windpipe and into your lungs where it enters the bloodstream. It then travels through the blood bound to hemoglobin – a protein found in red blood cells – to oxygenate the cells, tissues and organs of your body.

Oxygen saturation (SpO2) is a term referring to the concentration of oxygen in the blood, or the percentage of hemoglobin molecules that are saturated with oxygen. One hemoglobin molecule can carry 4 oxygen molecules.

How is Oxygen Saturation Measured?

pulse oximeter oxygen saturation levelYour oxygen saturation level can be estimated with a pulse oximeter, a small medical device that clips onto your finger. You can click here to view and purchase the pulse oximeter sold directly on the Inogen online store. The most accurate way to measure oxygen saturation, however, is through a blood test known as an arterial blood gas study.

Normal blood oxygen level ranges between 95-100%. It’s not uncommon for people with lung disease to have below normal levels. In general, supplemental oxygen is prescribed when the oxygen saturation level stays at or below 88 percent. It’s normal for oxygen saturation levels to fluctuate with activity. If your oxygen saturation level runs low on an ongoing basis, whether at rest, during activity or while you sleep, talk to your health care provider about using supplemental oxygen.

Signs and Symptoms of Low Oxygen Levels

In order to function properly, your body needs a certain amount of oxygen circulating in your bloodstream at all times. When the level of oxygen in the blood drops, hypoxemia, or low blood oxygen levels occur. Hypoxemia can lead to hypoxia, or low oxygen in the tissues. Ongoing hypoxemia in COPD can lead to pulmonary hypertension (high blood pressure in the lungs) and secondary polycythemia (an overproduction of red blood cells); it can also lead to other complications.

Although signs and symptoms of hypoxemia or hypoxia may vary from person to person, the following are the most common:[1]

  • Confusion
  • Changes in skin color from blue to cherry red
  • Fast heart beat
  • Fast breathing
  • Shortness of breath
  • Sweating
  • Wheezing and/or cough

How Oxygen Therapy Can Help

Treatment with supplemental oxygen increases the amount of oxygen in your bloodstream, which increases the amount of oxygen to your cells, tissues and organs. If you have a lung disease that impairs your breathing, getting more oxygen can help you breathe better and live longer. Whether you choose a home oxygen concentrator like the Inogen at Home or a portable oxygen concentrator like the Inogen One G3 or Inogen One G4, supplemental oxygen helps reduce the risk of hypoxemia or hypoxia by providing you with oxygen as needed or on a continuous basis, 24/7, Inogen has a solution for all your oxygen needs.


[1] WebMD. “Hypoxia and Hypoxemia”. Last reviewed June 12, 2014.

By Deborah Leader RN, BSN, PHN


12 thoughts on “Understanding Normal Blood Oxygen Level”

  1. Avatar Larry Deutschendorf says:

    Pleased with your info-very informative. What I need from you are the details needed to obtain the portable inogen. I need to know how much my cost is. I'm 79 years old. Be specific with your directions.

  2. Avatar Rodger Lewis says:

    I can never get a straight answer to this. Without me using oxygen, my oxygen levels, in just a matter of a minute or two, will go from the high 90%'s, like 97 or 98, then drop down to 85 or 84, and then go right back up to the high 90's, and go up and down like this all day long. What can cause this? I've had a cat – scan on every part of my body. I'm 72 years old. They see nothing really wrong with my lungs, but say I might have a little emphesemia? I also have a small cyst on my liver and one on my left kidney, but they say these are nothing to worry about. Is this dangerous and could it be caused by heart disease? I don't feel anything because of it. Since my blood oxygen level is above 93% for half of the time in every few minutes, am I getting enough oxygen to my organs? No one has the answer. They have me on oxygen but I really don't see much difference in my oxygen levels and what my oxygen does if I'm using it or not.

    1. Inogen Inogen says:

      Hi Rodger, When your oxygen levels drop like that do you experience any symptoms like coughing, wheezing or sweating? If so you could be experiencing hypoxemia and you need to go to the hospital right away. We cannot speak to the cyst on your liver and kidney as we have not examined you. In regards to your question about oxygen getting to your organs when you are at 93% – normal oxygen levels range between 95-100%. Values under 90% are considered low. At 93% oxygen saturation, you are lower than what is considered normal but higher than what is considered low, so it is important to continue to monitor your oxygen levels.

      For more information on oxygen levels, hypoxemia, and more, I've added a few links below. I hope this helps:

  3. Avatar Clay says:

    Weird. My oxygen levels float around 96 percent when I'm working or exercising or walking etc., But when I am at rest they fall..usually to around 93 give or take. That seems to me to be the opposite of what I would expect.

  4. Avatar gail macinnes says:

    Join the group Rodger … labile oxygen saturation PPHN in newborns. Mine go up and down like a yo-yo (74-99). No one seems to know and they like to tell me that my oximeter is off. I understand that as long as it doesn't stay low for more than 4 minutes at a time, there's no damage? Good luck to us.

  5. Avatar Brenda Lancaster says:

    Is there anyway for me to respond to Roger or Gail. I have the same problem with my oxygen going between low 80’s and high 90’s and no one able to understand why.

  6. Avatar Judith MAC says:

    Hi, Everyone…I just turned 71 and have been dealing with the same thing with my oxygen level vasilating like the rest of you. I am seeing a pulmonologist, and she has no answers. My cardio won't deal with it until the pulmonologist figures it out from her end and finds nothing, and she is not done with me yet. It takes two to three months to get into see either one of these docs in my area every time I need an appointment…so this is a very slow and frustrating process.

  7. Avatar Lisa says:

    I’m only 57, and my O2 fluctuates as well….between 93-99. I can sit with the meter on my finger and watch it rise and fall. I am going to try a new meter, but they have even seen this happen in the Dr’s office. No one has an answer.

  8. Avatar Alecia says:

    Has anyone considered dehydration during their o2 readings? Just a thought that popped into my mind. But sometimes you have to think outside of the box. Staying well hydrated and active helps the blood flow better and the muscles in check. I.e. diaphragm muscle. I just learned how to breathe without expanding my chest and only stomach area. As I use my pulse ozimeter I can see the stomach breathing far surpasses o2 levels of chest breathing.

  9. Avatar Lisa C Kirkland says:

    Hi, I have the same question, no answer, my difference is I have covid19 atm. My sats have steadily been creeping downward for the last week. From 84 at the lowest to 99. They continue to be super labile. Any ideas why this happens? I know the parameters for going Back to the ER. Just concerned about why they can be all over the place. I also have asthma and CVID.
    Any response is greatly appreciated.

    1. Inogen Inogen says:

      Please seek professional medical advice on this. We hope for a speedy recovery. Please ask your doctor about the TAV (Tidal Assist Ventilator) and call us at 855-MYINOGEN for any questions.
      Thank you!

  10. Avatar Ann Glendinning says:

    My pulmonary specialist is just starting with me. Lung function is good. My blood is not picking up the oxygen well enough. Mostly I have 91% oxygen when I measure it but it does go much higher sometimes and does dip into the mid to high eighties . He thinks it's a medication problem. Anybody have a similar experience?

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