A fingertip pulse oximeter shines light through the fingertip to estimate the percentage of oxygen in the blood. This can be an easy, relatively inexpensive, and noninvasive way to monitor your health, particularly if you have tested positive for COVID-19, have pneumonia, have a chronic lung disease, or have been diagnosed with another condition that requires monitoring your blood oxygen levels and pulse rates at home.

In just a few seconds, a fingertip pulse oximeter can approximate your blood oxygen level. A healthy person typically has an oxygen saturation, or SpO₂, of 95% or higher.

Medical professionals generally advise sick patients to reach out for medical care if their oxygen level drops below 95%, especially if they have other symptoms, such as shortness of breath. An SpO₂ of 92% or lower indicates that a patient may have hypoxia—a condition in which too little oxygen reaches the body’s tissues—which could be life-threatening. (Note, however, that a healthy person can also have low blood oxygen levels if they travel to a high altitude, said Dr. Luke Davis, a pulmonary and critical care specialist with Yale Medicine.)

Used under the guidance of a medical professional, an at-home pulse oximeter can help you track your health over time, arm you with data, and help you make decisions regarding your care. It can reassure you as you’re recuperating at home and warn you if you need to see a doctor.

At the same time, the FDA—which reviews manufacturer-submitted data for pulse oximeters and other medical devices—has cautioned that at-home pulse oximeters have limitations and can be inaccurate, particularly for people with darker skin tones The agency is in the process of reevaluating its requirements for manufacturers seeking FDA clearance. It advises people not to rely solely on a pulse oximeter to gauge their health and to instead pay attention to “all signs and symptoms,” and then to communicate them to a medical professional.

What about pulse oximeters for kids?

Some companies market fingertip pulse oximeters for use with children (many with cute animal faces, of course). In most cases, it’s fine to use a fingertip pulse oximeter that’s marketed for adult use on a child age 2 or older, as long as their finger fits snugly inside the device. (Oximeters used in medical settings for children under 2 are typically outfitted with sensors meant to be wrapped around a toe, a finger, or elsewhere on the body.) We did not consider any so-called pediatric fingertip pulse oximeters for this guide.

Consult a medical professional with questions about using a pulse oximeter with children.

To learn more about monitoring oxygen saturation and pulse at home, we interviewed four doctors who regularly use pulse oximeters in the care of their patients: Dr. Philip Bickler, chief of ​​neuroanesthesia at the University of California San Francisco and the director of the Hypoxia Lab, an independent, university-based facility that tests pulse oximeters and other medical devices;  Dr. Jason Adams, a pulmonary and critical care medicine physician at UC Davis Health; Dr. Luke Davis, a pulmonary and critical care specialist with Yale Medicine; and Dr. Tom Valley, a pulmonary and critical care physician and assistant professor of medicine at the University of Michigan. We also spoke with Dr. Noha Aboelata, CEO of the Roots Community Health Center, about the center’s 2023 lawsuit against makers and retailers of pulse oximeters.

I’m a senior staff writer for Wirecutter, where I cover everything from smartwatches for kids to COVID-19 rapid antigen tests. While evaluating pulse oximeters for this guide in 2022, I contracted COVID-19. Though I’d rather not have had COVID-19, my illness gave me the opportunity to use a variety of pulse oximeters while sick. (Indeed, the physician’s assistant I saw advised me to use one to track my blood oxygen level and to reach out if it dropped.)

Oxygen saturation is sometimes referred to as a fifth vital sign (in addition to temperature, pulse rate, blood pressure, and respiration rate). An increasing number of devices—from a phone that can act as a pulse oximeter to a ring that tracks blood oxygen levels during sleep—now promise to tell you if your blood contains a healthy amount of oxygen.

For this guide, we focused on fingertip pulse oximeters. Their main purpose is to estimate blood oxygen levels. Although we did test one pulse oximeter that connects to a smartphone app, we did not test pulse oximeters designed to collect data overnight and monitor symptoms of conditions like sleep apnea. We also did not test smartphones, smartwatches, or other wearables that claim to indirectly calculate blood oxygen levels. (We do, however, have separate reviews of the Oura Ring and Apple Watch, which tout SpO₂ and pulse-rate monitoring.) Though connected devices like these may be handy in a pinch, their reliability in pulse oximetry is not fully substantiated. Generally, these devices “are not quite ready for prime time,” said Jason Adams, MD, a pulmonary and critical care medicine physician at UC Davis Health.

The FDA recognizes two main categories of fingertip pulse oximeters.

Medical device pulse oximeters have been used in hospital settings for decades as a way to non-invasively monitor patients’ blood oxygen levels. These pulse oximeters are cleared by the FDA; many of the models we considered for this review have undergone additional independent lab tests. Most cost hundreds of dollars.

Most pulse oximeters sold in pharmacies and in big-box stores, however, are considered useful only for recreational or wellness purposes (you may find references to sports or aviation on their packaging), and they’re not considered medical devices. Although recreational pulse oximeters likely use similar technology, these devices technically do not have to be reviewed by the FDA before they’re sold to individuals. Some device makers still elect to be cleared by the FDA through its 510(k) process.

To determine which devices to test, we combed through reviews and other guides to pulse oximeters. We narrowed our selection by mainly looking for devices that have earned FDA 510(k) clearance; this means the manufacturers have shown that these devices are safe and effective, and that they perform “substantially” as well as a similar device (in this case, another fingertip pulse oximeter that has already undergone FDA review).

We also cross-checked contenders against Open Oximetry, a database of pulse oximeters created by members of the Hypoxia Lab at the University of California San Francisco. This database features a growing list of pulse oximeters that are sold to the public and have been independently tested for accuracy, reviewed by the FDA, or both. We eliminated devices with a poor performance record.

We found that a massive number of devices, variations, and distributors are in the pulse oximeter market—along with plenty of obfuscation of information. “Some of these devices claim they are FDA cleared, and when you look into it, the FDA was never involved. There is a lot of misinformation,” said Hypoxia Lab director Philip Bickler, MD, chief of ​​neuroanesthesia at UCSF.

We tested 10 devices that have either received FDA 510(k) clearance or, as shown in Open Oximetry, have been independently vetted in a lab. Some are both 510(k) cleared and independently vetted.

I first tested eight pulse oximeters on myself and half a dozen other people, including a 2-year-old, a 6-year-old, a 75-year-old, and a 78-year-old, as well as on people with both darker and lighter skin pigmentation. I personally tested the pulse oximeters in various scenarios: in direct sunlight, with nail polish on, after holding a handful of ice, mid-flight on an airplane, and during a week I spent sick with and recovering from COVID-19. Later, a panel of paid testers, who ranged in age, mobility, and skin tones, also tried our top picks.

At minimum, a pulse oximeter should have a display that includes not just SpO₂ but also heart rate, which is usually labeled as PR (pulse rate), bpm (beats per minute), or simply with a heart symbol. It should also include something that shows the strength of the signal, such as a pulsating wavelength or bar, Bickler said.

The gold standard for verifying the accuracy of a pulse oximeter is comparing the device’s readings with those of a blood test, called an arterial blood gas test, an invasive clinical procedure that directly quantifies the levels of oxygen and carbon dioxide in the blood, Bickler said. Fingertip pulse oximeters are more often tested in comparison with one another. To earn FDA clearance, device makers must show that a pulse oximeter is substantially equivalent—performs just as well as—an already-cleared device.

We evaluated FDA-cleared and/or lab-tested fingertip pulse oximeters based on two additional factors:

• Display: We looked for displays that were clear and simple to read and understand. We preferred displays that used contrasting colors and large lettering and numbering, making the labels, symbols, and results easy to see and interpret. We also considered whether the results could be accidentally misread.
• Comfort: We considered how comfortable the pulse oximeters felt to wear on the finger, including for a prolonged period of time. We kept them on for about 20 minutes at a time, to gauge comfort.

All of the devices we tested required minimal setup, apart from inserting AAA batteries (or, in the case of one device, charging via USB).

The Nonin Onyx Vantage 9590 is an ultra-reliable pulse oximeter that the FDA considers a medical device. Nonin Medical, which makes the Onyx Vantage 9590, also sells pulse oximeters intended for use in hospitals and other clinics. You may have seen the Onyx Vantage 9590 or a version of it in your doctor’s office.

It’s been clinically vetted. The Onyx Vantage 9590’s accuracy was confirmed in a study presented at the European Respiratory Society’s annual meeting in 2018. It also received FDA 510(k) clearance (PDF), and initial tests at Open Oximetry found that it was “one of the best performing fingertip devices we have tested.”

It performs better for people with dark skin than other pulse oximeters. In a 2024 study evaluating the accuracy of 11 pulse oximeters on patients with a range of skin tones, the Nonin Onyx Vantage 9590 and Masimo MightySat Medical pulse oximeters scored at the top. (See our review of the Masimo MightySat below.)

It’s straightforward to use. The device automatically turns on when a finger is inserted. A flashing light blinks red, orange, or green to indicate the strength of the signal (indicating that it is working; it blinks orange and then green as it determines that it can reliably measure the person’s SpO₂ and pulse). The numbers light up in red while the labels for SpO₂ (on top) and heart rate (a heart symbol, on the bottom) are in small, white lettering.

The Nonin pulse oximeter comes with a four-year warranty. It also seemed to be the sturdiest of all the pulse oximeters we tested, like it could withstand at least as many years of frequent use.

Flaws but not dealbreakers

It’s pricey. Although it’s not the most expensive pulse oximeter we considered, it’s much more costly than recreational-use pulse oximeters, like our budget pick.

The vertical display is basic. The display faces outward (for someone else to read), so if you are assessing yourself, you must bend your finger or turn it to face you. When reading it upside down, someone could accidentally mistake a healthy “98” for an “86.”

The Innovo Deluxe iP900AP pulse oximeter is reliable, easy to read, and comfortable to use—with one of the widest finger beds of any device we considered.

It performed solidly in independent clinical testing. Clinimark, a research and clinical laboratory for medical devices, tested and vetted the Innovo Deluxe iP900AP, according to Open Oximetry. But this pulse oximeter is marketed only for aviation, sport, and home use, and it has not received 510(k) clearance from the FDA—which is typical of pulse oximeters in this price range. Innovo’s website misleadingly claims that this pulse oximeter is “FDA cleared,” but it is simply registered with the FDA.

Sharp, contrasting colors make the display easy to read. The SpO₂ and pulse-rate levels light up in large, bright blue numbers, while their corresponding labels light up in bright orange. When you take your finger out of the device, or if your finger slips out, it reads “finger out” before turning off automatically. A small battery symbol indicates battery level (like most pulse oximeters, it uses two AAA batteries).

It offers six display options. Pressing the power button changes the display’s orientation, which includes both horizontal and vertical and facing you or facing away from you. It also offers either a blue pulsating bar or a blue waveform to show the signal strength.

It feels comfortable on the finger. Some testers said that the Innovo model felt the most comfortable, since it didn’t pinch as much as the other pulse oximeters we tried. It has a finger bed that is about 2.4 centimeters wide—among the widest of those on the devices we tested. Yet if you have smaller fingers, like one of the testers in our second group, it may not fit as well.

It is under warranty for one year. The pulse oximeter must be purchased from an authorized retailer to qualify for the warranty.

Flaws but not dealbreakers

One data point is too tiny to read. In addition to SpO₂ and pulse rate, the display shows your perfusion index. The perfusion index, which lets you know the strength of the blood flow in your finger, ranges from less than 1% to 20%. This data point is so small that it is hard to read on the device.

The auditory alarm feature on our test unit was ineffective. The Innovo pulse oximeter claims that an auditory alarm will sound if your SpO₂ and pulse rate fall below set limits, but we found the set limits unclear and confusing to set up. When I tested this device on an airplane, my SpO₂ fell briefly to 88%. Although the numbers flashed in warning, I did not (or could not) hear an alarm.

If you’re looking for a pulse oximeter that has been cleared by the FDA for over-the-counter medical use: The Masimo MightySat Medical is the only pulse oximeter to receive this designation. Masimo is similar to Nonin in that both companies make technology regularly found in hospitals and doctors’ offices. Like the Nonin Onyx Vantage 9590, the MightySat has been vetted in independent clinical tests, has received 510(k) clearance from the FDA, and ranks as one of the best-performing fingertip devices that have been tested by Open Oximetry. Its digital display is easy to read, and its over-the-counter designation means it comes with explicit instructions for how to use it at home. But the device is larger and bulkier than the Nonin, and it’s less intuitive to use (we noticed some of our testers couldn’t initially figure out which end opened for the finger). It also costs close to $300 (versus $200 for the Nonin) and is warrantied for two years (versus the Nonin’s four).

If you’re looking for an inexpensive pulse oximeter that you can pick up in a store, quickly: The Walgreens Fingertip Pulse Oximeter is a widely available device with an easy-to-read display. It’s listed for recreational use only and has not been cleared by the FDA. But this model (ChoiceMMed C20) was part of a study of six low-cost pulse oximeters, published in the journal Anesthesia & Analgesia, and it was one of two devices with results that were closest to the control readings. It is also listed in the Open Oximetry database. In a 2024 study that measured how well the Walgreens model estimated blood oxygen levels on people with a range of skin tones, it produced acceptable results, but it was not as accurate as the Nonin Onyx Vantage 9590 or the Masimo MightySat. Walgreens does not offer a warranty for the device.

If you’re looking for an alternative budget pulse oximeter: Consider the  iHealth Fingertip Pulse Oximeter. Though it’s sold through iHealth, this pulse oximeter is made by Contec (model CMS50DA), and similar models (such as CMS-50D and CMS-50DL) received 510(k) clearance. The display is easy to read, with the results in a large, bright blue font and the identification for SpO₂ and pulse rate in yellow.

Fingertip pulse oximeters gauge blood oxygen levels by clipping onto your finger, shining a light through the skin, and calculating the saturation of oxygen in your red blood cells.

To use one, insert your index, middle finger, or fourth finger. A pulsating bar, wavelength, or light indicates whether the pulse oximeter has a strong signal. Within seconds, it should tell you your SpO₂ and your pulse rate.

A healthy person has a resting pulse rate of 60 to 100 beats per minute and SpO₂ of 95% to 99%. Because a pulse oximeter provides an estimate of your blood oxygen level, your SpO₂ could actually be slightly higher or lower. It’s therefore important to watch for trends: If your SpO₂ starts to drop, it’s a sign that you should reach out to a medical professional, especially if it coincides with other factors, such as shortness of breath, chest pain, or a rapid pulse rate. Patients with low blood oxygen levels may need oxygen therapy.

Keep in mind that several factors can get in the way of an accurate reading, such as nail polish, direct light (PDF), your skin tone, and skin thickness (callused or especially thick skin can make it harder for the light to pass through). A pulse oximeter may also give you a low SpO₂ reading if your hands are cold.

You can check whether your pulse oximeter is reliable by taking it to a doctor’s office and comparing the results (as we did). You can also manually check your pulse rate and see if it matches the pulse rate on the device. If you’re already ill, you can have someone healthy test the pulse oximeter and compare the results. (Customers who bought a top-selling pulse oximeter on Amazon, the Zacurate 500DL Pro Series, have complained in reviews that their devices inaccurately gave them low results; you’ll know a pulse oximeter is inaccurate if a healthy person also receives a low result. The FDA encourages you to file a report if you’ve experienced a problem or injury that may have been related to your pulse oximeter.)

Another good rule of thumb is to test your blood oxygen level while you’re feeling healthy, to get a sense of your baseline. Doing so gives you an idea of the patterns in your blood oxygen level, since it can fluctuate throughout the day.

Data from a pulse oximeter can help detect changes in your health. During the early days of the pandemic, for instance, some COVID-19 patients were much sicker than they felt. Their blood oxygen levels turned out to be lower than normal, which was a sign that they needed more-intensive medical care. In general, many medical professionals advise patients with COVID-19 and other illnesses to track their blood oxygen levels while they’re recovering at home.

At the same time, a pulse oximeter should not be the sole means for assessing your well-being. Pay attention to other signs, such as any difficulty in breathing, said Luke Davis, MD, a pulmonary and critical care specialist with Yale Medicine. The American Lung Association cautions that not all pulse oximeters are created equal and that the pandemic has spurred “an upcropping of opportunistic manufacturers selling pulse oximeters as a medicine cabinet staple.”

Because of deadly problems that came to light during the COVID-19 pandemic, the FDA is currently evaluating its guidance on pulse oximeters. In particular, the FDA acknowledged that pulse oximeters have limitations, especially for people with darker skin tones. The theory is that darker pigmentation of the skin can interfere with a pulse oximeter’s light, and that pulse oximeters have not been designed and calibrated to account for that.

The accuracy of pulse oximeters is crucial. Its results can determine whether a patient, such as someone with asthma or another lung disease, receives care, medical intervention, or coverage through their health insurance. If pulse oximeters overestimate a person’s blood oxygen levels, that person may be denied the necessary health care.

That became the case during the COVID-19 pandemic. Researchers at the University of Michigan in 2020 found that fingertip pulse oximeters showed inaccurate results for some Black patients; this was especially problematic when overwhelmed hospitals had to send patients home to recuperate from COVID-19. The team reported that pulse oximeters were three times more likely to overestimate the blood oxygen levels of Black patients, making it more difficult to detect hypoxemia, so some people were less likely to receive needed treatment.

More recently, a 2024 study of 11 pulse oximeters on people with a range of skin tones found that most of the devices showed “a trend toward worse performance in participants with darker skin pigment.”

In November 2023, plaintiffs from Roots Community Health Center, in Oakland, California, filed a lawsuit against pulse oximeter makers and retailers such as Masimo, ChoiceMMed, and Walgreens. Its published analysis of COVID-19 treatment highlighted the disparity between Black and non-Black patients during the pandemic, pointing out delays with care.

Roots called on pulse oximeter makers to refine their technology so that people with all types of skin tones can expect to receive accurate results. In the meantime, it also demanded that manufacturers and retailers include a warning label on their packaging.

“Consumers need to be aware of any limitations of devices they’re using, especially if they’re using it to assess their health,” said Dr. Noha Aboelata, founder and CEO of Roots Community Health. “Not knowing about this can have disastrous outcomes and it has had disastrous outcomes already.”

Medical staff, hospitals, health insurance companies, and others also need to reconsider how they use pulse oximeters as a diagnostic tool.

“This has impact beyond the pandemic,” Aboelata said. “The technology needs to be fixed.”

For now, people with darker skin tones should be more skeptical of results from a pulse oximeter, said Dr. Tom Valley, a pulmonary and critical care physician and an assistant professor of medicine at the University of Michigan, who co-authored the 2020 research letter. People with darker skin should consider using a higher SpO₂ threshold for seeking medical care, and they should not necessarily be reassured by a “normal” reading, he said, especially when they’re feeling poorly.

“Pulse oximeters are still a valuable tool. I still use them every day,” Valley said. But “we need to acknowledge that these devices are imperfect, and they may be more imperfect for certain people.”

The Innovo iP900BP is a variation of our budget pick, another Innovo device, but it hasn’t yet been independently vetted by Open Oximetry. This pulse oximeter has a similarly bright and legible digital display.

The ChoiceMMed Black OLED Pulse Oximeter is made by Beijing Choice Electronic Technology Company; this particular model is the MD300C2F, which is not 510(k) cleared. The numbers light up in the same bright blue as on the Innovo model, and the labels for SpO₂ and pulse rate are the same bright orange; even the bright blue pulsating bar showing the signal strength is the same. Though it’s supposed to have one, ours did not have an indicator for battery level in the display.

The Contec CMS50DL Pulse Oximeter was the least expensive model we tested. We found it reliable, if basic, but potentially confusing to read compared with our picks. It was one of six low-cost pulse oximeters tested in a lab, with the results published in a peer-reviewed journal; of the six pulse oximeters, this Contec model was one of two that produced results in line with a blood test (that is, with less than a 3% margin). It also received 510(k) clearance. Although the numbers themselves are large and easy to read, it’s hard to tell which one is which—the labels for the pulse rate and SpO₂ are in minuscule, white lettering that’s hard to see (and it doesn’t help that the two results are the same size). If you are taking your own reading, you must also bend your finger or turn the device to face you so that it’s right-side up. One of our testers accidentally read the results upside down, thinking at first that their blood oxygen level was 86 instead of 98.

If you want a smart pulse oximeter, the iHealth Air Pulse Oximeter can link to iHealth’s smartphone app, to which it transmits readings via Bluetooth. (The iHealth MyVitals app, available for iOS and Android, connects to several iHealth devices, including the pulse oximeter, a wireless scale, and a blood pressure monitor. Although we’ve toyed with the app, we haven’t thoroughly tested it.) This pulse oximeter was the sleekest and most sophisticated-looking model we tested; it’s a monochrome white when off. The horizontal screen turns on when you press a button, displaying your SpO₂ on the left, your pulse rate on the right, and a pulsating up-and-down bar in the middle to indicate the signal strength. All words, numbers, and symbols light up in green. Depending on the amount of lighting in the room, we found that the display could be hard to read. The iHealth device received FDA clearance, but this model is not as easy to use as our picks. It charges only via USB and comes with only a USB charging cord (most fingertip pulse oximeters rely on AAA batteries and don’t require regular charging).

We tested the Zacurate 500DL Pro Series Fingertip Pulse Oximeter because it is one of the most popular pulse oximeters on Amazon (to date, this model has more than 224,000 ratings). A lab test found that the Zacurate model’s results were within the FDA recommended accuracy margin of less than 3%, according to Open Oximetry. Einstein Associates, the manufacturer, is registered with the FDA, but when we requested confirmation from a representative about 510(k) clearance, we did not receive a response.

Like the Contec pulse oximeter, the Zacurate model is a relatively inexpensive and basic pulse oximeter, with a vertical screen that lights up with the press of a button. All words, numbers, and symbols light up in red, with the SpO₂ on top in a slightly larger font, the pulse rate on the bottom, and a pulsating bar on the side to indicate signal strength. If you are taking your own reading, the vertical display faces you, so you need only hold up your hand to see the result. We found that it often showed a slightly low blood oxygen level for several seconds before climbing to the actual result.