How to use a Pulse Oximeter Correctly | Helpful Tips for Accuracy

July 10, 2022 - Parul Saini, Webmedy Team

Updated Version - July 8, 2023

With the growing popularity and usefulness of Pulse Oximeters, people are now using a pulse oximeter at home to monitor their blood oxygen levels.


In this article, we will give you helpful tips on how to use a Pulse Oximeter at home correctly to get accurate results.

What is a Pulse Oximeter?

A pulse oximeter is a small, clip-like medical device. It attaches to a body part, most commonly to a finger. A pulse oximeter uses a non-invasive method for monitoring a person's blood oxygen saturation (as opposed to measuring oxygen saturation directly through a blood sample). It can rapidly detect even small changes in oxygen levels. To know how a Pulse Oximeter works read this related blog article - What is a Pulse Oximeter?

Factors Affecting Pulse Oximeter Accuracy

First, let's go over the factors that can affect the accuracy of a Pulse Oximeter reading.

  • Incorrect Positioning of the Finger

    The finger should fit comfortably. It should not be too tight as it may restrict blood circulation. On the other hand, it should not be too loose for the device to fall off or allow outside light to interfere with the reading.

  • Nail polish on fingernails or Long dirty fingernails

    Nail polish or dirty nails can absorb the light emitted by the pulse oximeter and affect the accuracy of the test.

  • Movement of hand while taking the reading

    Movement of hand or shivering can result in an inaccurate reading.

  • Cold hands and Poor Blood Circulation

    Cold hands and fingers mean that the blood flow and circulation to your hand is low and may cause difficulty for the oximeter to detect a good pulse signal.

  • Current Tobacco Use

    A person who smokes heavily might cause their oxygen saturation to be measured at 8% higher.

  • Skin Thickness and Skin Pigmentation

    It has been found that dark skin or high pigmentation skin can result in overestimation of oxygen saturation, especially at low saturation levels.

  • Using under a Direct Bright Light Source

    Direct bright light in the room or bright sunlight can interfere and result in an inaccurate reading

Tips for taking Accurate Pulse Oximeter Readings at Home

  • Always follow instructions from the device manufacturer on how to take a reading.
  • Avoid taking the reading under a direct bright light source.
  • Take the test reading preferably sitting.
  • Make sure your hand is relaxed, warm, and below heart level.
  • The hand should be steady and in a resting position.
  • Preferably use the middle finger of your right hand. Remove any nail polish on the finger you are using.
  • Insert your finger into the device and press the button to start taking the reading. Wait at least 30 to 60 seconds until the reading stops changing and displays one steady number.

What are the two readings on a Pulse Oximeter?

  • Blood Oxygen Saturation (SpO2): The measurement that indicates what percentage of blood is saturated.
  • Pulse Rate: Pulse rate is nothing but the heart rate that indicates the number of times a heart beats per minute.

Interpreting the Pulse Oximeter Reading

  • A pulse oximeter reading is an estimate of blood oxygen saturation. For example, a pulse oximeter Oxyhemoglobin saturation (SpO2) of 90% may represent an arterial oxygen saturation (SaO2) of 86-94%.
  • Normal oxygen levels are at least 95%. Some patients with chronic lung disease or sleep apnea can have normal levels of around 90%.
  • If your SpO2 level is less than 95%, you need to visit a doctor, as it may be an indication that you may be suffering from hypoxia, a condition that requires observation and treatment.
  • When possible, make diagnosis and treatment decisions based on trends in pulse oximeter readings over time, rather than absolute thresholds.

Pay attention to Other Symptoms of Low Oxygen Level

Do not rely only on a pulse oximeter reading to assess your health condition or oxygen level. If you are monitoring your oxygen levels at home, also pay attention to other signs or symptoms of low oxygen levels, such as:

  • Difficulty in breathing.
  • Bluish color in nails, face, or lips.
  • Fast or racing pulse rate.
  • Tightness or pain in the chest.
  • A cough that gets worse over time.
  • A general feeling of discomfort and restlessness.

We hope, these tips will make you confident in using and getting accurate readings with a pulse oximeter at home.

Helpful Information

What is a pulse oximeter?

A pulse oximeter is a non-invasive medical device that measures the oxygen saturation level in your blood. It provides an estimation of the amount of oxygen that is in your blood, along with heart rate measurements. This information is crucial for various medical reasons, including assessing lung function, monitoring health during or after surgical procedures, and managing certain health conditions.

How does a pulse oximeter work?

A pulse oximeter works by emitting light at two different wavelengths from one side of the probe, and a sensor on the other side measures the amount of light that makes it through. Depending on the oxygen saturation in the blood, different amounts of these light wavelengths will be absorbed. The oximeter then calculates the difference and displays the oxygen saturation percentage.

How do I correctly place a pulse oximeter?

The pulse oximeter should be placed on a fingertip, ideally the index or middle finger. Make sure your hand is warm, relaxed, and held at heart level. It's important that the finger is free of nail polish or artificial nails as they can interfere with the readings.

What are the common mistakes to avoid while using a pulse oximeter?

Common mistakes include using it on cold fingers, moving too much during the measurement, and using it on a finger with nail polish or artificial nails. Also, you should not rely solely on the oximeter readings if you're feeling unwell - always consult with a healthcare provider if you have health concerns.

How often should I check my oxygen levels with a pulse oximeter?

The frequency of checking oxygen levels can depend on the individual's health condition. Some may need to check it multiple times a day, while others might only need to check it occasionally. Always follow the advice of your healthcare provider.

Can nail polish or artificial nails affect a pulse oximeter reading?

Yes, nail polish, especially dark or metallic colors, and artificial nails can affect the accuracy of pulse oximeter readings. These materials can interfere with the light transmission, leading to incorrect results.

What is the normal range for pulse oximetry readings?

For a healthy individual, a normal pulse oximeter reading is typically between 95% and 100%. Readings under 95% could be a sign of insufficient oxygen supply, but it's important to interpret these readings in conjunction with other signs and symptoms.

What should I do if my oxygen saturation level is low?

If your oxygen saturation level is consistently below 95% and you're feeling unwell, seek immediate medical attention. Low oxygen saturation levels could indicate a problem with your lungs or heart, or other health conditions.

Can I use a pulse oximeter on any finger?

Although the pulse oximeter can technically be used on any finger, it's typically recommended to use it on the index or middle finger for most accurate results. The ring finger and little finger can be used but are typically less reliable.

How should I clean my pulse oximeter?

Clean the pulse oximeter gently using a soft cloth dampened with water and mild detergent. Avoid getting liquid inside the device. Also, make sure the device is completely dry before using it again.

Is it normal for oximeter readings to fluctuate?

Yes, it's normal for readings to fluctuate slightly due to factors such as body position, breathing rate, and even altitude. However, significant or persistent fluctuations could be a sign of a health problem and should be checked by a healthcare professional.

Does movement affect the accuracy of a pulse oximeter?

Yes, movement can affect the accuracy of a pulse oximeter. It's recommended to stay still during the measurement process to ensure accurate readings.

Can cold hands affect pulse oximeter readings?

Yes, cold hands can affect pulse oximeter readings as coldness can decrease blood flow to the fingers. Warm your hands before using a pulse oximeter if they are cold.

Can a pulse oximeter detect heart problems?

While a pulse oximeter measures oxygen saturation and pulse rate, it's not designed to diagnose heart conditions. However, abnormal readings can indicate potential heart or lung problems that require medical attention.

Can I use a pulse oximeter for sleep apnea detection?

A pulse oximeter can be used as part of the diagnostic process for sleep apnea, but it can't diagnose the condition on its own. A comprehensive sleep study (polysomnography) is typically necessary to diagnose sleep apnea.

Can pulse oximeters be used on children or infants?

Yes, but they require pediatric pulse oximeters which are designed for smaller fingers. Always consult a pediatrician for usage guidelines and interpretation of results.

How long does it take for a pulse oximeter to read accurately?

It generally takes between 5 to 10 seconds for a pulse oximeter to provide a reading, though it can take up to a minute in some cases if peripheral circulation is poor.

What are the limitations of pulse oximeters?

Pulse oximeters can give inaccurate readings with poor circulation, cold fingers, nail polish or artificial nails, and in cases of severe anemia or carbon monoxide poisoning. Skin pigmentation can also potentially affect readings.

Can I use a pulse oximeter if I have dark skin?

Yes, but keep in mind that very dark skin pigmentation can potentially affect the accuracy of the reading. However, most modern pulse oximeters are designed to account for skin pigmentation differences.

How does altitude or smoking affect pulse oximeter readings?

Altitude can affect oximeter readings because oxygen concentration in the air decreases at higher altitudes. Smoking can lead to lower oxygen saturation levels due to carbon monoxide in the blood, which pulse oximeters cannot differentiate from oxygen.

Are smartphone pulse oximeter apps as accurate as standalone devices?

Generally, standalone pulse oximeters are considered more accurate than smartphone apps, especially for medical purposes. Smartphone apps may provide useful information for general wellness or fitness tracking, but they should not be relied upon for medical decisions.


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