We tested products from Nonin, Contec, Innovo, Masimo, and others to find the best pulse oximeters on the market
By Clark Tate ⋅ Senior Review Editor ⋅ Aug 24, 2022
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To help you find the best pulse oximeter, we researched dozens before buying the top 13 to test side-by-side. With so many options available, choosing the right one for you can feel overwhelming, especially when prices vary widely. We tested almost all of these pulse oximeters on both dark and light skin and under hypoxic conditions with the help of a professional freediver to gauge their consistency, comfort, and durability. We also dove into research studies to support our accurate results. The results are outlined below, so keep reading to find the right model for your needs and budget.
The Nonin Onyx Vantage 9590 is the only pulse oximeter we tested that is considered medical-grade and may require a prescription. A study in the European Respiratory Journal compared Nonin readings to actual arterial readings on 94 patients, and the results correlated quite well. It was the best of the three pulse oximeters tested, which helped give us more confidence in its readings. Because of this study, we used the Onyx Vantage as a benchmark in our accuracy testing. It performed consistently and provided the most rapid results, with an average response time of just over three seconds. It is also the only device that claims to work well with all skin tones, for patients with poor circulation, and even those wearing fingernail polish.
Studies show that pulse oximeters can dangerously overestimate oxygen levels in a percentage of very sick patients, and they are more likely to do so with dark-skinned patients. Nonin claims they have solved this issue, citing a study showing that the Onyx Vantage only significantly overestimates oxygen levels when they fall below 70%. Since normal oxygen saturation is 95% or above, it did better catching early SpO2 dips than the other two options tested. We didn't notice any difference in the readings between our dark-skinned and light-skinned testers, though they were healthy with normal blood flow and oxygen levels. Pulse oximeters tend to work well under those conditions. The only downsides we uncovered are that this device is expensive, doesn't record any of your data, and may require a prescription. But if you want a medical-grade device, ask your doctor about this one.
Most of these pulse oximeters are over-the-counter models not intended for medical use. Prescription pulse oximeters must undergo clinical accuracy testing and FDA review. They are used by doctors, in hospitals, and by anyone with a prescription from their doctor. All but one of the devices we review here are "general wellness products" for sports, aviation, or altitude use and are not required to achieve FDA approval (though the Contec is FDA approved for wellness use). The Nonin 9590 is the exception. It would be best if you had a prescription to purchase it directly from the company, though some commercial distributors don't require one.
A reputation for accuracy, impressive performance in our consistency testing, and low price point make the Contec CMS50DL Finger Tip monitor the best all-around pulse oximeter for general wellness use. While we didn't compare these pulse oximeters to actual arterial blood gas (SpO2) numbers (the gold standard for testing oxygen levels), others have. A 2016 study in Anesthesia & Analgesia found that the Contec met the International Organization for Standardization (ISO) criteria for accuracy when used on healthy subjects. It's also approved by the Food and Drug Administration, gave us fast and consistent readings in our tests, and reacted quickly to oxygen changes during our breath-hold testing. Additionally, we appreciate the pulse rate bar graph, which lets you know if your blood flow is high enough to get a good reading. It helps that the Contec is fairly comfortable and incredibly easy to use. Just place it over your fingernail, press the power button and wait for a reading. It turns off automatically and quickly when you're done.
While Contec claims this device will support 30 hours of continuous use, it's only meant for spot checks, so you won't really notice. It also doesn't store and chart your oxygen levels and pulse rate changes like some of the higher-tech versions we tested. A Nonin study (read: competitor sponsored) found that the Contec struggles to accurately detect low oxygen levels in patients with cold hands (cold hands are more likely if you're sick.) It's important to note that Contec is not intended to be a medical device, according to the manufacturer. It's intended to help athletes nerd out about their body metrics or to help plane pilots or passengers track oxygen levels. Bottom line: if you want to track your SpO2 levels while you're healthy, this is the one for you.
The Innovo Deluxe iP900AP monitor is a comfortable and reliable option that performed well in all of our tests. We appreciate how easy it is to use. Just insert the included batteries, and it quickly reads your SpO2, pulse rate, and perfusion index (PI). At the same time, it gives you plenty of customizable options. You can set up high and low SpO2 or pulse rate alarms, turn on a (really annoying) alert beep, adjust the display brightness, and rotate the display readout to face you or a care nurse — all by manipulating its one power button (just keep those instructions handy.)
The display also helps you determine how reliable the readings are. If the perfusion index is below 0.3%, you may not have enough blood in your hands for an accurate reading. You should warm them up with a cup of tea, a short walk, or other light movement. Similarly, the pulse rate bar should be above 30%, and the plethysmograph waveform (which measures your blood flow) should show consistent wave heights before you trust a reading. This device feels exceptionally sturdy, and we appreciate that it helps you get an accurate reading. If you don't need an app to record your readings, the Innovo Deluxe is a high-quality option.
The Masimo MightySat delivers a wealth of health information quickly and consistently. It tracks more data than any other device in our test, including blood oxygen saturation (SpO2), pulse rate, respirations per minute, perfusion index (PI), and pleth variability index (PVi), which can help you or your doctor manage your fluid intake. Its SpO2 and pulse rate measurements were comparable to the other devices we tested. It stores all of this data via the Masimo Personal Health App, and you can change the readout orientation on the device by tapping the bottom of the display. What we really love about this option is its comfort. Its clever double hinge and wide shape distribute pressure evenly across a padded cradle. Like Nonin, Masimo claims that its devices work accurately with darker skin tones.
We expected a lot based on this unit's price, and you do get more data with the MightySat. But if you don't know what those health metrics mean, they don't do you much good. And despite the impressive data collection, this is not rated as a medical device. It also reacted slower than the Contec during our breath-hold testing and didn't seem to register oxygen readings below 90% (you should call your doctor if your levels fall below 95% — levels at or below 90% are a 911 emergency according to NYC Health). While we liked the iPhone version of the app, the Android option is more difficult to use. But our biggest complaint with the MightySat is its huge price tag. Still, if you want an extremely comfortable device for quick check-ins on important health metrics, this one might be a good choice.
The Wellue SleepU Wrist (powered by Viatom) is meant to continuously monitor oxygen saturation levels while you sleep. It snaps on like a watch with a small and flexible finger loop which is very comfortable, keeping any weight off your finger. The ViHealth app captures and charts your data while you rest (as long as you leave it on for over two minutes). The app is not the most user-friendly, but it doesn't take long to master and provides plenty of information, letting you set vibration alerts if your SpO2 levels drop or pulse rate falls below or rises above certain thresholds. During breath-hold testing, the SleepU vibrated every time our freediver tester experienced hypoxic contractions. A USB cable recharges the device.
Though the SleepU provided consistent and accurate readings for all of our testers, it did take twice as long to register the first reading for our Black tester than our White testers. Since it's meant to monitor over a longer period, the extra 10 seconds doesn't seem like a big deal, but it does give us pause. The SleepU also has many small pieces, is harder to put on, and is more delicate than many other options. The finger loop is one-size-fits-all, which may not accommodate all fingers, and it's expensive. These things aside, it could be the one for you if you need to monitor your oxygen levels while getting a good night's sleep.
We didn't immediately notice the cartoon polar bear on the face of the Zacurate Children Digital, but we must admit it's pretty cute. Designed for quick oxygen level check-ins for children 2-12 years old, the cuteness is intentional. Aside from the kid-friendly facade and very small finger port, this non-medical device operates just like the other fingertip devices. Simply press the polar bear's nose (we love this), let him eat your finger, and you'll have a SpO2 and pulse rate reading in about seven seconds.
The device also gives you a waveform to help you gauge how consistent your kiddo's blood flow is and thus how accurate a reading is likely to be. Since it's designed for child-size fingers, the Zacurate is quite small, and we often struggled to get it to register our adult hands, even when using our pinkies. However, when it did, its readings were consistent and in line with the most accurate devices we tested. We recommend this model for anyone looking to monitor their child's oxygen stats.
Why You Should Trust Us
After reams of research, we rounded up a group of the most popular pulse oximeters on the market to test extensively. Our team checked their oxygen saturation during multiple rounds of testing while at rest, taking averages and timing how long each display took to get its first reading. We also tested them during dry, static apnea training for freediving, with breath holds lasting up to 3 minutes and 45 seconds and oxygen levels dropping to 80%. Then we tested each device against the Contec and Nonin options, which have research-backed accuracy levels. Afterward, we assessed them consistently, took notes on ease of use, and compared their comfort and features. Our testing metrics for this review are broken down into five comprehensive testing metrics:
Accuracy and Consistency (30% of overall score weighting)
Ease of Use (25% of score)
Features and Versatility (15% of score)
Comfort (15% of score)
Quality (15% of score)
This review is headed up by Clark Tate, an avid athlete who loves data. Clark held a Wilderness First Responder certification for a decade and has a Master's Degree in environmental science. Her experience reviewing scientific research and monitoring vital signs helped her test and compare these devices. Clark also consulted with a professional freediver, Ryan Reed, to test them in hypoxic conditions. Clark has light skin, so she additionally recruited a local business owner, Michele Morris, to test the pulse oximeters on Black skin and to provide another perspective on how easy, comfortable, and accurate each model is to use.
Analysis and Test Results
We gathered real-world data from healthy testers to identify the most outstanding pulse oximeters for your needs. Our detailed data and use notes helped us compare the devices head-to-head. Below, we expand upon each testing metric, outlining which models excelled in each area.
Pulse oximeters vary wildly in price, which is why we highly recommend the Contec CMS50DL. Its research-backed accuracy and ease of use make it a good choice for simple blood oxygenation and pulse rate spot checks. The Contec is our top recommendation for both value and performance. There are other options if you want more features, but you'll end up dishing out more cash.
Accuracy and Consistency
To know your true oxygen saturation rate, you need a blood sample from an artery to find your arterial blood gas. This is a painful and somewhat risky procedure, and we did not test these pulse oximeters by this high standard. But others have. They found that the Contec and Nonin provide more accurate readings than most when blood oxygen levels are low.
Of the two, the Nonin Onyx has more research backing its efficacy. Some research also supports its claim that it provides more accurate readings for those with darker skin tones. It is the only FDA-approved medical device in this review. The other pulse oximeters we reviewed are meant for wellness checks for athletes or aviation use. They're meant to be used by relatively healthy people and are not medical devices.
Pulse Oximeter Limitations
Pulse oximeters send beams of infrared light into your fingernail's capillary bed to measure changes in light absorption in your blood, indicating how much oxygen it's carrying. Because of this, things like skin color, thickness, circulation, skin temperature, and even nail polish can affect the accuracy of readings.
A 2022 study published July 11th on JAMA Internal Medicine and covered by NPR found that relying on pulse oximeter readings lead intensive care staff to administer less oxygen to Asian, Hispanic, and Black patients than to White patients. The NPR article mentions that new technologies my soon address this very important failing.
A 2020 study in The New England Journal of Medicine found that hospital-grade pulse oximeters were three times as likely to miss low oxygen levels in Black patients than in light-skinned patients, missing it in around 11% of Black patients and 4% of White patients.
The New York Times ran an article responding to the 2020 study. They interviewed doctors who argued that pulse oximeters can still be a useful tool to monitor oxygen levels as long as you understand their limitations. It's a good idea to reach out to your doctor for more information on these complex topics.
Considering the research, we rank the Nonin Onyx as the most accurate monitor in our review, followed by the Contec. When we tested each monitor against these two standards, all of them gave us comparable oxygen saturation numbers — within one percentage point. We tested this by attaching all three monitors to a finger on one hand, then took several readings before rotating them through the different fingers to account for any circulation issues. We found that these devices work well for healthy people with good circulation.
While pulse oximeters may be useful for estimating blood oxygen levels, these devices have limitations that can result in inaccurate readings. Patients with conditions such as COVID-19 should not rely solely on pulse oximeter measurements to monitor their health at home as they are not a substitute for a medical diagnosis by a health care provider.
We think the same New York Times article that responds to the pulse oximeter racial bias study provides a useful counterpoint.
When we averaged readings from our standard tests, most of the devices were similar, giving us average readings of 98% or 99%. The average for the Wellue O2Ring was 96%. If you go for that one, just know it tends to run lower than other options. The iHealth total was also a bit low at 97%.
What Should Your SpO2 Be?
Normal readings range between 95% and 100% according to the Mayo Clinic. According to Yale Medicine, readings below 92% are a sign of hypoxia, and any reading below 88% should spur you to seek immediate attention.
We did test the device's performance in hypoxic events on light-colored skin with the help of a professional freediver, who conducted several rounds of dry, static breath-hold training (from 2.5 to 3.5 minutes) with each device. We tested the devices in pairs to have a comparison point; most dipped to between 80% and 88% SpO2. The Wellue O2Ring dipped down to 74%, and the Masimo stayed at 90% or above. The Wellue O2Ring, Contec, Wellue SleepU, and Innovo were more reactive than the others, tracking changes more closely.
Ease of Use
Generally, pulse oximeters have user-friendly interfaces. That said, we tested units ranging from high-tech to superbly simple. While we wouldn't say that any of these are difficult to use, the four options that link to your smart device via Bluetooth are certainly more complex. The Wellue SleepU and Wellue O2Ring options use the same ViHealth app.
We found the app easy to navigate even when toggling between the two devices. It clearly displays readings in real-time and makes it easy to scroll through your history. The readouts on the devices themselves are harder to see.
We struggled more with the Masimo Personal Health app. It doesn't catalog past recordings clearly by date, though it works well in real-time. The display is large, easy to read, and rotates to face you or a caretaker. The iHealth Air Wireless app is bright and cheery and maps long-term trends for you. We also like the on-device display. The problem with this pulse oximeter is how often the display blanks out.
Of the app-free options, the Nonin is the easiest. It turns on automatically when you insert your finger and offers the fastest response time, giving you a reading in just over three seconds on average. The rest are similarly simple — you just need to press the power button first. We appreciate the Innovo, Mibest OLED Finger Pulse, Santamedical Generation 2 OLED, and Zacurate Children options that let you rotate their display, so it's easy for you to look at it no matter what finger you place it on.
Features and Versatility
All of these pulse oximeters measure your blood oxygen saturation and pulse rate. Quite a few include more detailed information. The Masimo MightySat offers the most comprehensive health data, especially compared to the more simplistic machines we reviewed. This model measures SpO2, pulse rate, perfusion index (PI), respiration rate (RRp), and pleth variability index (PVi) and stores everything in its companion app.
Having an app to store your data is a big plus, particularly if you're not good at documenting your measurements. Apps also emphasize interesting data like any concerning oxygen level drops. For that reason, we rate the MightySat quite high. The Wellue O2Ring Wearable, Wellue SleepU wrist-mounted monitor, and the iHealth options are high in the features category as well. The Wellue Fingertip stores 12 readings in the device itself, an intermediary step that we appreciate.
Most of these devices are meant to take a spot check, which is a pulse rate and Sp02 check at a single moment in time. All three Wellue options are also meant to monitor your oxygen profusion constantly. The fingertip version allows you to toggle back and forth between a spot check or continuous monitoring setting.
A number of these devices also give you additional information — like a perfusion index score, a pulse rate bar, and a waveform photoplethysmograph — to help you determine if you're getting enough blood flow for an accurate reading. The Innovo monitor gives you all three indications, as does the MightySat. The AccuMed CMS-50D Fingertip and Santamedical give you the pulse bar and the waveform. The iHealth gives you your perfusion index in its app readout, and the Nonin, Contec, Mibest, Wellue Fingertip, and two Zacurate options provide a pulse bar.
What Do All of Those Numbers Mean?
Basic models offer just a couple of data points, and fancier devices often provide more. To understand the data, you'll need to know these abbreviations:
SpO2 stands for oxygen saturation. SpO2 measures the amount of oxygen in your blood at a given time. It is measured as a percentage of the total oxygen your blood is capable of carrying.
PR or HR stands for pulse rate or heart-rate, respectively. They are interchangeable and describe how many times your heart beats every minute. Your PR will change constantly based on your body position, activity level, or emotional state.
PI or perfusion index describes how much blood is in your non-pulsatile or peripheral tissues. A low PI number may indicate that you don't have enough blood flow in your fingers for an accurate reading.
PVi stands for pleth variability index. Pleth is short for photoplethysmograph. The pleth waveforms are the waves that show up on the bottom of some of the monitor displays. The pleth waveform indicates the strength of your pulse and how much blood is moving through your capillaries.
Brpm stands for breaths per minute or respiratory rate. It measures how many breath cycles you take every minute. It can reflect how well your heart and lungs function in day-to-day movement or while recovering from exercise.
Most of these devices are meant for spot-checking your oxygen levels. But even if you just have the device on your fingertip for a minute or two, it's nice if it's comfortable. If you need or want to monitor your oxygen level trends over time, you'll appreciate not feeling like your finger is in a vice.
The Wellue O2Ring and SleepU monitors are meant to monitor your pulse and oxygen levels while you sleep. They are exponentially more comfortable than their fingertip clip counterparts. Of the two, we prefer the wrist monitor since it divides its weight and bulk between your finger and wrist. Still, we don't mind sleeping with either device or wearing them for hours during the day.
The MightySat is the most comfortable of the fingertip monitors. The hinge doesn't hold pressure on your fingertip, spreading it evenly across your first two joints instead. The cushioned port is really nice — this is the only hinged monitor we would want to wear for any amount of time.
The rest are fine. Certainly comfortable enough for a speedy spot check. The Nonin and Contec monitors are some of the least comfortable in the review. They are short and don't distribute pressure very well, leaving you with fingertips that feel like they've lost a little circulation. We don't love the iHealth either since it forces you to find a comfortable palm-up resting position.
To gauge material quality and durability, we rolled these devices around on our fingers, tugged on the hinges, and looked closely at the battery door tabs. In general, these are robust devices that will perform their task reliably if you treat them as well as a smartphone.
The fingertip monitors seem more robust than the wearable options. Both the Wellue SleepU and O2Ring have a ring monitor that is not meant to be compressed, so don't sit on them or toss them in a bag. We saved the boxes they came in for safekeeping.
Of the clip-style monitors, Innovo strikes us as particularly robust and well made. Its battery door tabs and hinges are easy to operate, the hinge is well-contained, and the plastic feels very sturdy. We are pleased with how the screen shrugged off inevitable scratches and wear. The Nonin seems similarly high quality, with a pleasant spring on its battery door and scratch-free facade. We also appreciate that the AccuMed and Zacurate options come with protective rubber covers.
Most of the remaining monitors give us little cause for concern, though. The screen on the Contec ended up with more scratches than the rest, and the AccuMed received a few too. And while the MightySat seems very well-made, the battery door is hard to open and seems like it could easily break. The iHealth hinges chattered quite a bit, often closing a little out of line.
Don't forget your mask
Finding a top-ranked face mask can potentially help keep germs that can impact your oxygen levels at bay. Check out our lineup of impressive masks.
The quest for a pulse oximeter can feel complicated, given the scientific jargon and many abbreviations. We're here to help. To pick the best monitor for your needs, first figure out when you'll use it and why. From there, you can decide which features are right for you. Good luck and good health.
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