After doing more than 10 hours of research, interviewing three experts, spending an extraordinary amount of time sitting with a thermometer under our tongues, and confirming nearly 100 times that a human body can maintain a healthy temperature even during a heat wave, we found the two best thermometers for at-home use. If you’re looking for an oral/rectal/axillary thermometer, our top pick is the Vicks Comfort Flex Digital. If you’re looking for an ear or forehead thermometer, we recommend the dual-function iProven forehead and ear DMT-489.
The Vicks Comfort Flex Digital was faster than any thermometers in its class. The clear, backlit display is larger than those on its competitors and delivers easy to read measurements. The fever alarm—which lights up the display in green, yellow, or red depending on the temperature reading—is a straightforward guide for anyone unsure of what qualifies as a temperature.
Although adults may appreciate the speed of ear and forehead thermometers, where these devices really shine is when you’re taking a kid’s temperature. The iProven switches easily from forehead to ear functionality and features an easy to read, color-coded display that takes the guesswork out of classifying a fever.
We started the search for best thermometer by diving into the recent research on the subject, looking at what science says about the benefits and drawbacks of each of the different types of thermometers. Then we spoke to three physicians for their opinions on the best thermometers for at-home use. Dr. John Mills, an infectious disease specialist at the University of Michigan, talked to us about adult thermometer use. For kids, we spoke to Dr. Suzie Roberts, a New York–based emergency department pediatrician, and Dr. Sahib El-Radhi, pediatrician and author of a 2014 article on ideal thermometers. We also read reviews presented by Consumer Reports, Thoroughly Reviewed, and Parenting.com, as well as customer ratings on many retail sites.
Contrary to popular belief, “Do I feel warm to you?” is not a medically accepted way of determining if you have a fever. If you’re still relying on that method, you should invest in a thermometer and take out the guesswork.
Thermometers for at-home use don’t need to be recalibrated (in other words, if it was accurate when you bought it, it should still be), so if you have one that fits your needs and still turns on, this isn’t a product that needs to be constantly replaced. But newer thermometers offer features like faster read times, better displays, and fever alarms, all of which can make life a little easier when you’re sick and cranky. If you have a kid, the upgrade to a forehead or ear device may take some of the struggle out of measuring a temperature.
We tested these thermometers keeping in mind that they would be for children who were at least 6 months old and adults. They were not tested for rectal use on newborns, and the three methods we looked at (oral, ear, and forehead) are not recommended for that age group.
Digital thermometers have made difficult-to-read mercury thermometers obsolete. They come in several formats—the key is to find a user-friendly thermometer that offers accurate and consistent readings with the least amount of discomfort.
Oral temperature taking is probably the most common for at-home use and is still the standard in many doctor’s offices. These stick thermometers are simple and offer reliable measurements and fast results, but you do need to keep your mouth closed around the device. This is tough for most toddlers and preschoolers, so they are recommended for anyone age 5 and up. Oral thermometers today usually pull triple duty as axillary (armpit) and rectal thermometers as well. We opted to focus on these multipurpose thermometers rather than ones that offer only one option—where you decide to put it is up to you.
Most thermometers we tested covered a range from roughly 96℉ to 109℉ with an accuracy of ±0.2℉1 (the numbers were also listed in Celsius, but we’re going to speak in Fahrenheit here because I’m an American trained to reject the metric system). Some report lower accuracy at higher ranges, but if your temperature is pushing 107℉, odds are you’re in a hospital and not at home quibbling over a 0.4℉ difference.
In addition to the oral variety, you can now get affordable ear and forehead models for use at home. Ear (or tympanic membrane) thermometers measure temperature based on heat radiated through the tympanic membrane or eardrum. While it’s tempting to just place the device in an ear and press the button, these thermometers are a little more complicated than “insert and wait,” so make sure to follow the directions to pull out the shell of the ear to line things up. The Mayo Clinic does not recommend these thermometers for newborns; Mayo advocates a minimum age of 6 months—basically when children are old enough to balk at the rectal thermometer but too young to manage an oral one. Dr. Suzie Roberts pointed out, “The ear thermometer may not give the most accurate readings, but it is the easiest to perform on a moving, uncooperative toddler. A lot of parents also don’t feel comfortable using a rectal thermometer. At home, I use an ear thermometer with my toddler and an oral for my 7-year-old.”
Forehead (or temporal artery) thermometers measure temperature based on heat radiated from the temporal artery running across the forehead—all it takes is a light touch of the thermometer to the forehead. Some thermometers in this class also offer a “no touch” feature that takes an infrared reading from the skin with no contact necessary. On the downside, results from these thermometers may be affected by things like sweating and air temperature (taking the temperature itself may not wake up the sick person, but wiping the sweat off his head first will probably do the job anyway). While research consistently shows that rectal temperatures in children are most accurate, some studies done recently on children suggest that, when used correctly, measurements from forehead thermometers are close to those obtained rectally.
Forehead and ear thermometers are convenient, but you’re sacrificing a little bit of accuracy—user manuals report an accuracy ± 0.4℉, which is twice the variability you’ll find in an oral or rectal thermometer. That’s an obvious drawback, but things like ease of use and comfort are almost equally important (even the most accurate thermometer in the world won’t do you any good if you can’t use it on a wailing child). These thermometers tend to be a little more expensive than the simpler oral models, but they’re worth the investment when speed and comfort are top concerns.
Infrared, no-touch thermometers are now available, but there isn’t much hard data on their use in home settings. The idea of a no-touch thermometer that won’t risk waking a sick kid is incredibly appealing, but we stuck with the evidence-supported forehead method.
For adult at-home use, Dr. John Mills says he would buy an oral thermometer, citing an article published last year in the Annals of Internal Medicine that specifically focused on adult temperature readings. Researchers looked at studies that compared temperatures taken centrally (internally—via the pulmonary artery, bladder, or esophagus) with ones taken peripherally (oral, tympanic membrane, temporal artery, axillary). Not surprisingly, they found that central methods were always more accurate. That’s important to know in the hospital, but telling someone at home with a cold to take their temperature through their bladder isn’t exactly a viable option. Mills explained the takeaway of the study for people at home: “Researchers concluded that if you have to use a peripheral thermometer, oral or tympanic membrane are the best to use, followed by temporal as a third option. In medicine we are always a little wary of new technology—if your device is complicated or you are unable to use it properly, it may not be as reliable. With oral thermometers, there is more clinical and home experience, it’s easy, uses the simplest technology, and is the cheaper option. I would use oral first and then tympanic membrane.”
However, this is in contrast to a small 2014 study that suggested temporal artery thermometers are more accurate than ear thermometers in children. No word on what difference in adult and child foreheads might cause this difference. In our own tests, we found both forehead and ear thermometers to be accurate within the stated 0.4 degree, which is good enough for at-home use.
Our requirements for a thermometer were simple: something fast, accurate, and easy to read that doesn’t require putting on glasses. As someone who grew up sharing a room with a light sleeper, I also know a thermometer for kids should be fast, painless, and, ideally, silent to minimize the risk of waking either the sleeping patient or ta (hypothetically) cantankerous sibling.
Once we knew which categories we wanted to look at, we chose thermometers based on customer ratings and best selling items on Amazon and those suggested by major product review sites like Consumer Reports, Thoroughly Reviewed, and Parenting.com. Then we narrowed things down by considering the features like backlit displays, or color-coded systems that flash to indicate whether a temperature is normal, a low-grade fever, or a high-grade fever. We also looked for devices that were easy to clean, rather than ones that require disposable protective caps or sleeves.
Rectal thermometers are still considered the gold standard—they offer the most reliably accurate measurement of core body temperature. Roberts explained that rectal thermometers are recommended for use with newborns because “they are most accurate and it is important to know if a newborn really has a fever. A fever in a newborn of more than 100.4℉ degrees will get a full medical workup including blood, urine, and cerebrospinal fluid analysis”—it’s critically important to get as accurate a reading as possible on babies. Even though it remains the most accurate measurement, rectal temp is going to be a hard sell past infancy. For the older crowd, there are other, less invasive ways to go, and those formats are accurate enough for the purposes of home use.
One of the features we were most interested in was the ability to silence a thermometer. The alert that the reading is done is key when you’re taking your own temperature, but when you’re using it on someone else and can clearly see the display, silence is golden. This feature is unexpectedly rare though—we’ve explicitly mentioned the thermometers that include it in our Competition section, but for our top picks, the other benefits outweighed that flaw.
Before you start thinking about factors like ease of use and extra features, the most important aspect of a thermometer is always going to be its accuracy and consistency in measurements. The user manual of every thermometer includes the range of temperatures it measures and its accuracy within that range, so we’re going to assume that those numbers are valid. But that doesn’t mean at-home results don’t matter. I tested each thermometer five times on myself (a healthy adult with no fever) and compared those at-home results to readings from a Welch Allyn Spot Vital Signs LXi, the thermometer used in urgent-care clinics in New York City.
Thermometers are used by people of all ages, so we called in a senior tester, 95-year-old Sidney Kirschner, who was generous enough to spend his afternoon repeatedly taking his temperature in exchange for a Hershey bar. Because Kirschner didn’t schlep to a clinic for a comparison temperature test, his job was to judge how easy it was to use.
We looked at how close the measurements we got at home were to the professional thermometer and how long it took to give final measurement. Although the ear and forehead thermometers all gave results in less than three seconds, operating time for oral thermometers ranged from 8 seconds to an excruciating high of 60 seconds. A minute may not seem like a long period of time, but it is when you’re sitting around with a stick of plastic under your tongue.
To find out how a forehead thermometer worked in the outside world, we tested one on a healthy person sitting in the sun. The reading came back as 103.8℉—a lesson in both thermometer use and the need to sit in the shade. You can follow all of the instructions (wipe off sweat, wait after exercise), but the environment around you is still going to influence your skin temperature. Engineers at Braun explained that it “takes 28 minutes to adjust to a new setting”—in other words, you and the thermometer need to be in the same steady room for a half hour before it will give you an accurate read.
In the end though, almost all of the thermometers tested gave readings consistent with the professional-grade thermometer. The real deciding factor here is the features, so let’s focus on those.
For the oral/rectal/axillary thermometer, we recommend the Vicks Comfort Flex Digital, which stands out in speed and style. The average measurement time of 8 seconds was the fastest tested—beating our runner-up by 3 seconds and the slowest thermometer tested by more than 50 seconds. Amazon reviews for the product consistently mention the speed as a key feature. The backlit, large display was by far the easiest to read and interpret—Sidney Kirschner chose this thermometer without hesitation because, he said, “I can actually see the numbers.” Plus, it was the only model we tested that comes with a useful, color-coded fever alarm.
Half of the thermometers we tested had small numbers in a display window roughly 0.75 by 0.2 inch. The Vicks featured numbers twice the size of the next largest display and was the only thermometer with a backlight feature—a must have for anyone who shuns the light when sick or anyone taking a child’s temperature in the dark.
Vicks was also the only thermometer with a useful fever alarm. Most of the thermometers we tested boast alarms that change the number or tone of beeps when a temperature is elevated—a feature that is completely useless unless you memorize the “normal” beep structure in advance. The Vicks thermometer, on the other hand, color codes the results, turning green for a normal temperature, yellow to indicate a slightly elevated temperature above 99℉, and red to alert you to a fever greater than 101℉. (Note that a fever in children over 6 months old is defined as starting at 99℉ for oral temperature and 100.4℉ for rectal temperature, which are both in the alarm’s yellow zone.) No preternatural ability to interpret shrill beeping required.
Like the other thermometers in its class, the Vicks thermometer stores the most recent reading. The thermometer comes with a user manual, a one-piece case, and five single-use probe covers. These covers are trashed after one use so they won’t last you very long. You can buy replacements, but the thermometer is water-resistant so save your money—an alcohol swab or soap and water on the tip between each use will work just fine.
The Vicks thermometer has an annoying, repetitive alert that can’t be silenced. Although this was the case with every model we tested, the Vicks’s beep was particularly grating. Reviewers at Parenting.com agree on our observed strengths and weaknesses, complimenting the speed and color coding of the thermometer but complaining that “the beeping is a bit loud.”
Our version of the Vicks thermometer was also Fahrenheit only. For us this was a flaw, but it would almost certainly be a dealbreaker for people who think in Celsius. Kaz Incorporated, the makers of this thermometer, told us that newer versions can be switched between the two scales, but currently many retailers are still selling off their existing Fahrenheit-only inventory.
Many of the negative reviews on Amazon and Drugstore.com are complaints that the battery was either dead or died after a few uses. We used ours over two dozen times for more than two weeks and had no problems, so we can’t comment on that. The 3-volt, CR1225 battery is easily replaceable, but when you buy a new item, it should work—if yours is a dud, send it back.
With the cap in place, the thermometer is designed for use on the forehead—that’s when you use the button labeled Head. When the cap is removed, it reveals an ear measurement tip—here you press the aptly named Ear button. A traditionalist, Kirschner still preferred the oral thermometer, but, after a brief tutorial, he found the iProven easy to use and liked the instantaneous readings and the clear, backlit screen displaying his temperature. Like on our top pick oral thermometer, this screen is also color coded—green for a normal temperature, light green for a temperature above 99.5℉, pink for above 100.4℉, and red for a temperature of 101.4℉ or above. It also allows you to measure a room’s ambient temperature by pointing it at the ceiling (I don’t have a thermostat, so I couldn’t test the accuracy on this, but it certainly felt like the 82℉ it reported in my apartment).
The last 20 measurements are stored in the device’s memory. The user manual reports a range of 89.6℉ to 107.9℉ for forehead measurements and 32℉to 212℉ for the ear with a range of ±0.4℉. No word on why you would possibly need an ear thermometer that runs up to 212℉.
In what seems to be a consistent problem with thermometers sold for at-home use (presumably no one designing them has tried to take the temperature of a sleeping kid), you cannot silence the alarm.
Instead of a case/cover, the iProven comes with a storage bag. This feels less protective than something solid and plastic and also can’t be cleaned easily. On the other hand, some Amazon reviews explicitly mention this as a positive as it makes the device easier to transport. One man’s flaw …
*At the time of publishing, the price was $20.
The first, and most significant, issue is that there’s no display on the thermometer itself—the Kinsa is only functional when it’s plugged into an iOS or Android device. This requires a smartphone near the sick bed at all times, which is both annoying and, far more damningly, eliminates anyone without access to smartphone as a possible user (Sidney Kirschner tapped out on this one). To use the thermometer, you plug it into the headphone jack, open the app, and press the Take Temperature button. An average of 12 seconds later your phone clearly displays the reading. Because the thermometer is operated via app, it is the only oral thermometer tested that can be silenced.
Once the results are in, you have a few options—close the app with no further interaction, add the temperature to your created health profile, or add in any symptoms associated with your temperature (the app offers 12 options, but you can also add notes or pictures with additional details). The app is intuitive, bright, and well-designed, and I would never use it again once the novelty had worn off. It does integrate with Apple HealthKit and, in the future, an account system will allow you to share data with people on different devices, giving multiple caregivers health updates. If you have an elevated temperature, the app also offers you medical advice from the Mayo Clinic—I am instinctively wary of any app that plays doctor like this, but at least it’s taking information from a reliable source.
Our second major complaint was that the device plugs directly into the headphone jack, which leaves you awkwardly balancing the phone in front of your face. The thermometer comes with an extension cord that allows you to leave the phone on the table, but it’s not a common cord and for many families that kind of add on will disappear forever after one illness. This may not be a complete dealbreaker with oral temperatures—but if you’re using it rectally, that’s a whole separate story.
Also, this is a silly little nitpick, but it tasted funny.
There is one additional feature that is worth mentioning: The app also allows you to share details of your illness with community organizations like schools, improving our ability to track the epidemiology of disease (if these devices were widely adopted, the public health implications cannot be overstated). For all of our complaints about the Kinsa, it’s the only thermometer we tested whose features became a topic of dinner conversation.
Finally, though you might be tempted by its ability to track temperature readings, standard fever thermometers like the Kinsa are not ideal for fertility tracking. Talk to your doctor before settling on the right thermometer for taking basal body temperature.
With the exception of the smart thermometers, which require syncing with an app, none of these require any real setup. All come with batteries either preinstalled or in the box. No maintenance other than basic hygiene is needed. Don’t skimp on cleaning a thermometer after you’ve used it—that’s gross.
We live in a world where you can tell your house to turn on the air conditioner before you get home. Reliable smart thermometers that connect to phone apps through Bluetooth (and display the temperature on the device) should be in the not too distant future.
Hopefully more companies will start including a silence feature in their devices.
We tested a total of 10 oral thermometers, each selected based on online reviews or top sellers.
The form and function of the Generation Guard MT-4320 perfectly matches those of our runner-up pick, the Nanci Perrin. It’s a few dollars more, but it’s a solid alternative if that thermometer is not available.
We nixed a few options based on display size and read time: The Lite Sensations Rapid Digital Thermometer had a small display and a 25-second measurement time. The Veridian 08-352 clocked in with an average read time of 38 seconds. The iProven DT-K 117A featured a small, difficult to read display window.
The CVS Flexible Tip Digital Thermometer had a nice big display, but we found the readings to be inconsistent.
The Walmart ReliOn takes far too long to deliver results, with an average reading time of 40 seconds. The owner’s manual also cites an accuracy half that of our top and runner-up picks. The average measurement time of the Metene 311 was 46 seconds with a horrifying high of 60 seconds. Saving $5 is not worth spending an extra 30 seconds of life with a thermometer under your tongue. Hard pass.
The Braun Thermoscan ear thermometer requires lens caps for use (literally requires—the device will not operate until one is snugly in place). In a setting where the device will be used on multiple people with no time or resources to clean it between uses, this thermometer is an excellent option. For at-home use though, the need to keep an added component in stock makes it unappealing.2
The Innovo thermometer was another great forehead and ear combination device. Physically it’s almost identical to the iProven, but instead of clearly labeled buttons, the Innovo device inexplicably has them marked as F1 and F2 with the legend on the bottom of the handle. It’s a small change, but an irritating one that complicated its use, and limits its user base to people who can read the legend (Sidney Kirschner couldn’t make out the words) and those who can quickly interpret it.
The Pyle Digital Ear Smart Thermometer was less accurate than the Kinsa and is slightly less comfortable to use.
We liked that the forehead Exergen TAT 2000-T, can be silenced but, unlike our recommended pick, the process is way more complicated and required some careful reading of the instruction manual. It also has a small, hard to read backlit display and was less intuitive to use than the Braun (for example, you need to press the main button 10 times to turn the alarm on and off). It also runs on an (included) 9-volt battery—I generally try to avoid devices with batteries that I can’t replace by raiding the remote.
(Photos by Michael Hession)
Originally published: October 3, 2016