Pulse Oximeter Chart – Safe, Normal & Low Blood Oxygen Levels

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blood oxygen levels

When using a pulse oximeter at home, it is important that you understand what the readings mean.

What exactly is the impact of safe, normal & low blood oxygen levels, and how should you respond?

Essentially, blood oxygen levels are important as they provide information on how blood cells are transporting oxygen around the body.

Each cell can carry up to four oxygen molecules, and you clearly need a good supply to keep vital organs such as the heart and brain working at optimum levels.

In short, vital systems need a normal percentage of oxygen inside your blood at all times.

This is known as oxygen saturation, and you use a pulse oximeter to measure this.

Blood Oxygen Saturation Levels


Pulse Oximeter Readings

Oxygen levels are measured in relation to the percentage of oxygen saturated in your blood. In medical terms, this is your SpO2 level.

Normal Blood Oxygen Levels

The normal blood oxygen saturation rate is between 95% and 100%.

‘Concerning’ Blood Oxygen Levels

If oxygen concentrations fall between 91% and 95%, it is a cause for concern. This signifies an underlying medical problem and it is advised that if you have a reading in this range, that you contact your healthcare provider.

Low Blood Oxygen Levels

Low blood oxygen rate is medically defined as percentages that fall below 90% oxygen saturation. In short, readings at this level indicate a medical emergency. You should call 911 immediately if blood oxygen saturation falls this low

Below 85% Oxygen Saturation Levels

If a patient’s oxygen saturation level falls to 85% or below, the brain is being adversely affected due to lack of oxygen. Symptoms include vision changes or loss of vision and total blackout.


If blood oxygen saturation levels fall to around 67%, Cyanosis will set it.

The lack of oxygen being transported by your blood cells, causes a blue tinge to develop on your skin. Your mouth, lips, and beneath your fingernail matrix will be affected first, followed by the spread occurring over the rest of your body.

Final Words

Understanding blood oxygen saturation levels is very important when using a pulse oximeter at home. If you take a reading lower than 95% you now know that action does need to be taken.


About Hannah Drake

Hannah Drake, RN, CSP is a registered nurse and owner and founder of Nurse Focus. Her nursing career spans almost two decades, and in that time she has developed her skill base across a variety of settings, including med surg nursing, clinical informatics system administration and implementation, and healthcare community management. Contact Hannah.

3 thoughts on “Pulse Oximeter Chart – Safe, Normal & Low Blood Oxygen Levels”

  1. Your color chart is seriously in need of help. The light text is almost impossible to read even the two columns on the right are hard to read. Seriously someone needs to do a little quality check on this page.

  2. You seem to have a notation error for the O2 Oximeter Chart and the written description below the chart. ” >= 90% Low Blood Oxygen Levels”. The notation you are using is incorrect; “>= ” means Greater than or equal to any value that is listed to its left, which in this case is assumed to be the value for Oxygen saturation. You need to reverse the symbol to : <= , which would indicate an O2 value LESS THAN or EQUAL TO 90% represents "Low Blood Oxygen Levels", which is obviously your intent.

  3. For the orange box above, with 91%, I think it would be less than 91, not greater than. I believe the > sign above should be <


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