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Pulse oximetry is a quick, safe way to check the oxygen level in your blood. Typically, a healthcare provider clips a small device on your fingertip and gets a reading within seconds. Some pulse oximeters attach to other places, like your toe or ear. A normal oxygen level is 95% to 100%.
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Pulse oximetry is a quick, painless way to measure your heart rate and the level of oxygen (oxygen saturation) in your blood. A small device that clips onto your fingertip, a pulse oximeter uses light to figure out your oxygen level. Many consider pulse oximetry a vital sign. Healthcare providers use it to diagnose a low level of oxygen (hypoxia). It can warn your provider that your oxygen level is low before you have symptoms.
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Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy
A pulse oximeter (pulse ox for short) is a device that measures your heart rate and oxygen level. Often, it’s a hinged clip that you put your finger inside. But the device can also attach to disposable tape that a healthcare provider wraps around your finger, toe, earlobe or nose.
Providers use these devices in hospitals and medical offices, but you can also buy one to use at home. Some pulse oximeters have a wire probe you attach to your ear, toe or finger. For infants, healthcare providers may use pulse oximetry on their arm, foot or other places. A pulse oximeter has a wire or cable that powers it and sends data to a monitor.
The device can show two or three numbers:
Your healthcare provider may use a pulse oximeter at various times in your life, like when you have:
A pulse oximeter analyzes the light it shines through your finger. The device can tell how much oxygen is in your red blood cells by looking at the light a protein in those cells absorbs. It does the math for you and shows you a number.
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You don’t need to do anything to prepare for this test, unless you want to remove dark nail polish. Removing this makes sure the light is able to get through your nail and finger.
A healthcare provider will usually clip the pulse oximeter over your fingertip. But they can also attach a pulse oximeter to your toes, ears, foot, nose or forehead. You may see a red light from the device. This is harmless.
This decades-old test is safe and noninvasive. But some people have an allergic reaction to the adhesive from the kind of device that sticks to your skin. Long-term use can cause blisters or damage to your nail. Another disadvantage is that a pulse oximeter may give an inaccurate reading in some situations. This can happen if you have:
If a healthcare provider is checking your oxygen level at a routine appointment, they’ll remove the pulse oximeter once they get a reading. If you’re in the hospital, you may have a pulse oximeter checking your oxygen level nonstop. You can let your provider know if the device is causing any discomfort with long-term use. They can move it to another area so your skin doesn’t get irritated.
It only takes a few seconds to get results from pulse oximetry. You can see the numbers on the device’s screen or monitor.
You should get a percentage of oxygen saturation. You want to see a number higher than 92%. A normal level is from 95% to 100% for all ages. You might have a lower number if you have lung disease or live in a place with a higher elevation. Your results may be slightly higher or lower than results from a blood sample. An arterial blood gas test is more accurate. You should also see a pulse number. A normal resting heart rate is 60 to 100 beats per minute for adults.
If you have a low oxygen level, you may need oxygen therapy. This is because all of your cells need oxygen to work. Not getting enough oxygen can damage your organs.
Contact a provider if your oxygen saturation is 92% or lower at home. Get medical help right away if it’s 88% or lower. This means your body isn’t getting enough oxygen. If your resting heart rate is outside the normal range, contact your provider.
A loved one is in the hospital and has a device on their fingertip. You can rest easy knowing it’s not hurting them. This trusted device is watching over your loved one’s oxygen levels in a noninvasive way. But you can let your loved one’s care team know if you think a pulse oximeter is causing discomfort. A provider should be able to move it elsewhere.
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Last reviewed on 09/23/2025.
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