Blood Oxygen Level Chart: Ranges, Symptoms, Monitoring

Ian C. Langtree - Writer/Editor for Disabled World (DW)
Published: 2022/09/01 - Updated: 2025/05/21
Publication Type: Informative
Category Topic: Medical Calculators and Charts - Academic Publications

Page Content: Synopsis - Introduction - Main - Insights, Updates

Synopsis: This information provides a comprehensive overview of blood oxygen saturation, detailing how it is measured, what constitutes healthy and concerning levels, and the implications for various populations, including seniors and people with disabilities. It explains that healthy oxygen saturation typically ranges from 95% to 100%, while levels between 91% and 94% warrant close monitoring, and levels at or below 90% suggest a need for medical consultation.

The article outlines the use of pulse oximeters and smartwatches for non-invasive monitoring, as well as more clinical tests like arterial blood gas analysis. It also lists common causes of low oxygen levels, such as chronic lung diseases, anemia, and high altitude, and describes symptoms including chest pain, bluish skin, and shortness of breath.

This resource is particularly helpful for individuals managing chronic respiratory conditions, caregivers, and healthcare professionals, as it offers practical advice on accurate measurement, interpretation of results, and when to seek medical attention. The authoritative nature of the information is supported by clear explanations, practical tips, and a focus on accessibility for people with disabilities and seniors, making it a valuable reference for monitoring and understanding blood oxygen health - Disabled World (DW).

Defining Blood Oxygen Saturation

Blood Oxygen Saturation: Oxygen is carried around in your red blood cells by a molecule called haemoglobin. In medicine, oxygen saturation, commonly referred to as "sats", measures the percentage of hemoglobin binding sites in the bloodstream occupied by oxygen. Oxygen saturation is the fraction of oxygen-saturated hemoglobin relative to total hemoglobin (unsaturated + saturated) in the blood. The human body requires and regulates a very precise and specific balance of oxygen in the blood. Normal arterial blood oxygen saturation levels in humans are 97-100 percent. If the level is below 90 percent, it is considered low and called hypoxemia. Arterial blood oxygen levels below 80 percent may compromise organ function, such as the brain and heart, and should be promptly addressed.

Introduction

When you breathe, oxygen goes through your lungs and enters your bloodstream. The amount of oxygen in your blood is called your blood oxygen level (blood oxygen saturation). Your body needs a certain amount of oxygen to function correctly. Low blood oxygen levels can lead to severe health conditions. Your blood oxygen level is the percentage of the amount of oxygen circulating in your blood.

Main Content

Measuring Blood Oxygen Level

Pulse Oximeter

A pulse oximeter is a small device that clips onto a finger, an earlobe, or an infant's foot and uses light beams to estimate the oxygen saturation of the blood (how much oxygen is in the blood) and the pulse rate. Oxygen saturation gives information about the amount of oxygen carried in the blood. The pulse oximeter can estimate the amount of oxygen in the blood without drawing a blood sample. They are used often in hospitals and clinics and can also be bought to use at home.

Using a Pulse Oximeter:

NOTE: Several factors can affect the accuracy of a pulse oximeter reading, such as poor circulation, skin pigmentation, skin thickness, skin temperature, current tobacco use, and fingernail polish. To get the best reading from a pulse oximeter:

Always follow the manufacturer's instructions for use.
Sit still and do not move the part of your body where the pulse oximeter is located.
Wait a few seconds until the reading stops changing and displays one steady number.
Write down your oxygen levels with the date and time of the reading so you can easily track changes and report these to your health care provider.
When placing the oximeter on your finger, make sure your hand is warm, relaxed, and held below the level of the heart. Remove any fingernail polish on that finger.

Smart Watches

Some smartwatches can measure your blood oxygen saturation level. For example, in the Apple Watch Series 6 and above, the optical heart sensor has also been redesigned to add blood oxygen measurement capabilities. During a blood oxygen measurement, the back crystal shines red and green LEDs and infrared light onto your wrist. Photodiodes then measure the amount of light reflected. Algorithms use this data to calculate the color of your blood. The color determines your blood oxygen level - bright red blood has more oxygen, while dark red blood has less.

Other Blood Oxygen Level Test Methods

Blood gas test
Hypoxic challenge (fitness-to-fly) test
Long-term oxygen therapy (LTOT) assessment

A full Blood Oxygen Level Test will measure:

pH: Measures the balance of acids and bases in the blood.
Oxygen content (O2CT): Measures the amount of oxygen in the blood.
Partial pressure of carbon dioxide (PaCO2): Measures the amount of carbon dioxide in the blood.
Partial pressure of oxygen (PaO2): Measures the pressure of oxygen dissolved in the blood. It helps show how well oxygen moves from your lungs to your bloodstream.
Oxygen saturation (O2Sat): Measures the amount of hemoglobin in your blood. Hemoglobin is a protein in your red blood cells that carries oxygen from your lungs to the rest of your body.

Blood Oxygen Level Charts

Blood Oxygen Level Table
95-100%	Average for the population, The red blood cells are well oxygenated and sufficiently transport oxygen around the body.
91 - 94%	Below average for the population. Monitor closely.
90% or Less	Consider consulting your doctor.

Healthy individuals at sea level usually exhibit oxygen saturation values between 96% and 99% and should be above 94%. At 1,600 meters' altitude (about one mile high), oxygen saturation should be above 92%. Most people have 95 - 100% blood oxygen level. However, some people live normal lives with blood oxygen levels below 95%. Slightly lower values while sleeping are expected, and some users might experience values below 95%. Some people with chronic lung disease or sleep apnea can have normal levels of around 90%.

Printable Blood Oxygen Level Chart

Continued below image.

This image is a color-coded Blood Oxygen Level Chart that categorizes oxygen saturation percentages into three levels. The chart is divided into three horizontal sections. The top green section is labeled NORMAL and represents a blood oxygen level between 95% and 100%. The middle yellow section is labeled LOW and covers levels from 91% to 94%. The bottom red section is labeled DANGER and indicates levels at or below 90%, marked with ≤ 90%. The text is bold and easy to read, and the color scheme - green for safe, yellow for caution, and red for danger - helps quickly convey the urgency of each range.

Continued...

Symptoms of Low Blood Oxygen Level

NOTE: Some patients with low oxygen levels may not show any or all of these symptoms.

Chest pain or tightness.
Fast or racing pulse rate.
Restlessness and discomfort.
Bluish coloring in the face, lips, or nails.
signs or symptoms of low oxygen levels can include:
Shortness of breath, difficulty breathing, or a cough that gets worse.

Causes of Low Blood Oxygen Level Reading

Blood oxygen levels can get low due to low air oxygen levels as atmospheric oxygen becomes extremely low at high altitudes such as mountainous regions. Decreased capacity of the body to take in oxygen can be caused by lung conditions that include:

Asthma
Anemia
Smoking
Bronchitis
Pneumonia
Sleep apnea
Emphysema
Pneumothorax
Pulmonary edema
Pulmonary fibrosis
Interstitial lung disease
Acute respiratory distress syndrome
Viral infections such as COVID-19
Decreased capacity of the heart to supply the oxygenated blood back to the lungs from causes such as congenital heart diseases (heart defects present by birth).

If Your Blood Oxygen Levels is Low

Oxygen levels may be low if someone feels short of breath, is breathing faster than usual, or feels too sick to do their usual daily activities; even if a pulse oximeter says their oxygen levels are normal, it may mean you:

Are not taking in enough oxygen
Are not getting rid of enough carbon dioxide
Have an imbalance in your acid-base levels

These conditions can also be signs of a lung or kidney disease. A blood oxygen level test can't diagnose specific diseases, but your health care provider will order more tests to confirm or rule out a diagnosis if your results are not normal. If you have questions about your results, talk to your doctor or health care provider.

Insights, Analysis, and Developments

Editorial Note: Understanding blood oxygen levels is not just a matter of medical curiosity; it is a crucial aspect of daily health management for millions of people, especially those living with chronic illnesses, disabilities, or the effects of aging. By demystifying the process of measurement and interpretation, and by highlighting both the technology and the symptoms to watch for, this article offers practical guidance that can help prevent complications and support timely medical intervention. As wearable health technology becomes more common, such clear and accessible information will only grow in importance for individuals and caregivers alike - Disabled World (DW).

Author Credentials: Ian is the founder and Editor-in-Chief of Disabled World, a leading resource for news and information on disability issues. With a global perspective shaped by years of travel and lived experience, Ian is a committed proponent of the Social Model of Disability-a transformative framework developed by disabled activists in the 1970s that emphasizes dismantling societal barriers rather than focusing solely on individual impairments. His work reflects a deep commitment to disability rights, accessibility, and social inclusion. To learn more about Ian's background, expertise, and accomplishments, visit his full biography.