We may earn a commission from links on this page.The Powerbeats Pro 2 are a new set of headphones with a really interesting featureApple says they can measure your heart rate during workouts. Huge if trueimagine if you could leave your watch at home (or not bother to buy one in the first place) and still get a heart rate reading to go with your workout. But that's only going to be a useful feature if the data is reasonably accurate. I was curious how good a reading they can actually get from your ears, so I compared the Powerbeats Pro 2 to a traditional chest strap, and to the Apple Watch for good measure. So how do these headphones stack up against those established methods? Not well, Im afraid. Not well at all. Beats Powerbeats Pro 2 $249.00 at Amazon Shop Now Shop Now $249.00 at Amazon My first hint that the heart rate functionality may be a bit underwhelming was that Apple says on their support page for the Powerbeats Pro 2 that If youre wearing an Apple Watch during your workoutthe Apple Watch heart rate monitor data is prioritized, suggesting that the headphones heart rate data isnt as good as the Apple Watchs heart rate data, and they know it.Okay, so, maybe the headphones data is slightly less accurate, or slightly less reliable. But how much less? Ive been doing heart rate comparisons whenever I review or compare devices, wearing a chest strap alongside the device Im testing and seeing whether the device can keep up. For some examples, see my reviews of the Coros Pace 3 for a watch with an impressively accurate heart rate sensor, and of Whoop for one that tries hard to keep up, but doesnt always succeed.So I ran the same type of test for the Powerbeats Pro 2, and got some surprising datathat is, when I could get the headphones to pair and the compatible apps to play nice. The bottom line: These arent going to replace a heart rate monitor for serious athletes, and probably arent even good enough for casual use for anyone who wants to track their heart rate. But take a look at my results and see for yourself. The little black window next to the ear tip is the heart rate sensor. Credit: Beth Skwarecki How I tested the Powerbeats Pro 2s heart rate functionalityI took these headphones for several runs, some outdoors and some on a treadmill. I tried a variety of apps, but most of the data you see below is from tests done with Runna on iPhone (iPhone 12 Mini) and Strava on Android (Pixel 9). Outdoors, it was cold, and I wore a buff over my ears. Indoors, I was in a busy public gym, with nothing on my ears but the Powerbeats Pro 2.I did the same mini workout for each test, except where noted. This was:Two minutes warmup (if on a treadmill, this was a jog at 5-6 mph)Five rounds of one minute running (7.0 mph) followed by one minute walking (3.0 mph)No cooldownI typically rested or walked while reviewing my results and setting up the next test.(Quiz for those following my fitness coverage: is this a SIT or a HIIT workout? Answer key here.)I chose this interval workout because intervals do the best job of showing the performance of a heart rate sensor. If I just did a steady run, youd expect a more or less steady line, and wed be quibbling over whether the line is a little more (or less) wobbly than its supposed to be. But when my actual heart rate surges up and drops down repeatedly, its easy to see when a sensor lags behind, or doesnt quite reach the peak, or stays consistently too high or too low compared to the chest strap.A chest strap, by the way, is as close as you can get to a gold standard for heart rate field tests like this. I used my trusty Coospo paired to a Garmin 265S.For each of the graphs below, the data from both devices was collected at the same time. The software used to make the graphs is DC Rainmaker's analyzer.The heart rate data was often inaccurate or just plain uselessTesting a heart rate feature on a device is usually simple: I record a workout on the new device, compare to the readings I get from a heart rate chest strap, and report here on how it did its job. But testing the Powerbeats Pro 2 was more like solving a mystery. I believe Ive figured out what the heck is going on here, and its not good news.The first time I took the headphones out for testing, with the iPhone app Runna, I got laughably poor readingstwo or three data points each, instead of the hundreds that should have been there. Was it Runnas fault? The headband I wore over my ears on that cold day? Or are the headphones really that bad? Powerbeats Pro 2 in orange, chest strap heart rate monitor (for reference) in black. Credit: Beth Skwarecki For comparison, I did another interval run with the Runna app but using a Series 10 Apple Watch as the sensor. Apple Watches have always had pretty good heart rate sensors, and you can see the drastic difference here. (The Apple Watch is in red.) Apple Watch in red, chest strap heart rate monitor (for reference) in black. Credit: Beth Skwarecki Strangely, one of my tests that dayon an Android phone, with the headphones paired to the Strava appsaw the heart rate trace meander aimlessly, and then suddenly snap on to the true data for the second half of the workout. OK, so the headphones can report a correct heart rate, but when and how? And why dont they do it more often?More research was needed. The next day, I took the headphones to a gym to use the treadmill (meaning that there was no ear covering for the rest of my tests). With the headphones paired to an app on a phone in front of me, and my Garmin on my wrist, I could compare the two mid-run and clearly see that the headphones were just not doing their job in the heart rate department. The headphones would often report a heart rate that was far higher than what the watch was showing, often by 10 beats or more. (The worst I noticed was a 34-beat difference, where the headphones reported 168 while the chest strap was reading 134.) Sorry for the blurry photos, but this is a representative sample of what I saw while I was running. Heart rate is the bottom number on the watch. Credit: Beth Skwarecki I had to choose between sound quality and accurate heart rate readingsI gave this mystery a good long think. I thought about all the factors that may have influenced the readings. I checked out other reviews of the Powerbeats Pro 2, and saw that, while they were also disappointed in its performance, they got more usable heart rate graphs than I did. What could be going wrong?In the settings for the Powerbeats Pro 2, I noticed somethingan ear tip fit test. I had already selected the rubbery ear tips that fit my ears the best (XS), so I didnt think I needed this. But I did the test, and the app told me that I needed to adjust something, either the ear tips or the position of the headphones in my ears. I finally got a good seal by angling the headphones a lot further forward than I would have expected. The marketing photos typically show people with the ear hooks right in front of their ears, nearly vertical, but mine had to be pointing forward at least at a 45-degree angle for Apple to give me the all-clear. Maybe fit was the answer to my mystery. So I hit the gym again. Left: results of the fit test telling me I had a good seal. Right: instructions to wear the headphones in a way that did not give me a good seal. Credit: Beth Skwarecki (Fun fact: the fit test requires a quiet environment. I wanted to do the fit test immediately before my run, so I started it while standing on the treadmill at the gym. I got an error message saying my environment was too noisy. Oh well. I did my best to get the headphones in the same position as when I had done the test, and I made sure that it felt and sounded like I was getting a good seal.) Left: the results of the fit test, which felt and sounded great. Right: the only position I could find that got me good heart rate data (and terrible sound quality) Credit: Beth Skwarecki It turns out that fit was the answer, but not the way I expected. I ran with the ear hooks in their approved position, and got terrible readings. Often 20-30 beats too high, and occasionally the headphones would fail to send data to the app they were paired to, leaving a blank - - in the space where heart rate was supposed to appear.And then I had an idea. What if I deliberately fit the headphones as badly as possible? I cranked them backward so the ear hooks were vertical. The sound got tinny, the active noise canceling did nothing, and they kind of hurt. I could hear the guy on the treadmill next to me breathing and messing with his phone. You know, the stuff that you wear headphones to block out. But my heart rate data? It was nearly perfect. Top: wearing the headphones as recommended by the ear tip fit test. Bottom: wearing the headphones with ear hooks vertical and sound quality terrible. In both graphs, orange is the Powerbeats Pro 2 and black is the chest strap reading used for reference. Credit: Beth Skwarecki I did a few more tests in each headphone position, and confirmed thatwhether I paired them to an Android running Strava or an iPhone using RunnaI had the choice of two experiences:Uncomfortable fit, tinny music, poor audio seal, but good heart rate dataGood seal, comfortable fit, music sounds great, sounds of the gym are blocked outbut useless heart rate dataIm not sure if this is a me problem or an everyone problem. Maybe I have weird ears. But even if so, I cant be the only one with weird ears. Will you, dear reader, find that you pay $249 for a pair of headphones only to find one of their touted features is unusable? I cant tell you the odds, but I can tell you theyre much greater than zero.Oh, and youll have a green light shining from your ears How you'll look in dim light. Credit: Beth Skwarecki The first night I had the headphones, I used them in the evening while I was doing my nightly wind-down routine of playing word games while listening to music. (Yes, I use my phone in bed. Sleep experts, you may disapprove.) My husband was trying to sleep next to me, and I became aware of a bright green light somewhere in the room. Was it coming from some device of his? It sure wasnt anything of mine. Then I realized: It must be coming from my ears. (He looked over and groggily confirmed.)As with other photoplesmythographic devices, these things measure heart rate by shining a green light through your skin and measuring how much gets reflected back. This can be used to give a (theoretically) fairly accurate reading of your heart rate. Thats why the back of your smartwatch glows green from time to time, and why even the Oura ring (generations 3 onward) shines at you when youre trying to sleep. (I miss the Oura gen 2s decision to use non-visible infrared light, but those days are in the past. Sigh.)To confirm, I went to the Settings app on my iPhone, selected the Powerbeats Pro, and switched off heart rate sensing. The room went dark. I turned heart rate sensing back on. Green light again. I turned the sensing back off for the night, and then the next day was perplexed at why I couldnt get the heart rate feature working before I realized, duh, I turned it off.How to use the heart rate feature on iPhone Ironically for an Apple product, the heart rate feature is less accessible on an iPhone than it is on Android. The headphones pair nicely, and you get a dedicated section for them in the main Settings app, which is where you can adjust their noise-canceling or transparency mode, try the fit test, or turn heart rate monitoring on or off. But when it comes to actually using the heart rate feature during a workout, you need to use one of seven "partner apps." A reviewer's guide from Apple lists these as: Nike Run Club, Runna, Ladder, Slopes, Open (a meditation app), Peloton, and YaoYao (a jump rope app). Notably, there are no "just track a run" apps in this listno Strava, for exampleso even my testing was tricky. Nike Run Club is free, but doesn't export files that include heart rate data. Peloton is a paid app, and I couldn't find a way to export data without an active subscription (paid members may be able to export to Strava). Runna is paid, but I was able to use the "free run" feature on a free trial. Ladder is a paid workout app. Slopes is for skiingand admittedly I didn't try that one. Open is a meditation app, and I couldn't find any way to use it as a replacement for a workout app. Apple says that the data from your Powerbeats Pro 2 will end up in the Apple Health app, but it's not in any usable format like a graph of heart rate from your workout. Heart rate data as shown in the Apple Health app. The data next to a bluetooth symbol is from the Powerbeats Pro 2. I think. Credit: Beth Skwarecki The above is what you'll see if you go into Apple Health, then Heart Rate, then Show All Data.All right, how do you actually turn this on? Here's what I did. Pair the Powerbeats Pro 2 to your phone using the instructions that came with them. (You'll open the case, headphones still inside, near your phone. Then just follow the prompts.) Make sure the heart rate sensor is on (it is by default). Go into the Health app, then Heart Rate, then Data Sources and Access. Make sure your chosen app has access to read heart rate data. Do a workout from one of those partner apps (Runna, etc). How to use the heart rate feature on AndroidAndroid users, this is an easier one for you, and you have a much broader choice of apps. You can use any app that can connect to a bluetooth heart rate monitor, like Strava, or Wahoo, or Polar Beat. (I used Strava for my testing.) Pair the headphones as you would any Bluetooth headphonesDownload the Beats app if desiredI did this first, but it didn't seem to be necessary to pair the sound or heart rate.Go into your chosen appsay, Strava. Tap whatever icon or menu allows you to connect to a heart rate sensor.Double click and hold the "b" button on your headphones (either side works). So that's click, release, then click and hold.The Powerbeats Pro 2 should show up as an available heart rate sensor. Select it, and then go ahead and do your workout.The bottom line: Dont rely on the Powerbeats Pro 2 for accurate heart rate dataIf you train by heart rate in any kind of serious way, do not bother with this feature. Sometimes it may not work (as in my initial tests with Runna). Sometimes it may show that your heart rate is 15, 20, even 34(!) beats higher than it really is. Sometimes it may be correct, or close to correctbut if you dont know when a heart rate sensor is correct and when its way off, what good is it?This isnt just a small difference, either. If the headphones were a few beats off here and there, I wouldnt worry about it. But these 20+ beat discrepancies are enough to make you think youre in zone 4 when youre actually in zone 2 or 3. Thats enough to throw off your workout, and if this data ends up being used for a VO2max calculation, it will give you a wildly inaccurate idea of your cardio fitness. The heart rate data from the Powerbeats Pro 2 is just not good enough to do the job its trying to do. Which is sad! I wish this could work! But, alas, it does not.