Tips to Increase Accuracy of Heart Rate Monitor on Apple Watch

Nov 16, 2016 - 23 Comments

Increasing accuracy of Apple Watch heart rate readings

The built-in heart rate monitor feature of Apple Watch is great for exercise and monitoring general heart health, but from time to time you may notice the heart rate number reported back seems unusual given your present state. For example, you may be sitting at your desk working and see some number way out of line with your regular heart rate, or perhaps you’re exercising and you see a number much below what you’d expect. These outlier readings happen somewhat frequently on Apple Watch, but there’s usually a reason that is easy to address.

Wait for a Second BPM Reading

First, if you’re seeing a reading that doesn’t look quite right, be sure to leave the Watch heart rate glance active for another few seconds so that another reading or several can be taken. The latter readings tend to be more accurate if the first one is way out there, for example I’ve had readings tell me my heart rate was 150 BPM while sitting at a desk (come on I didn’t drink THAT much coffee!) but after letting the Watch read heart rate a bit longer, it jumped back into a typically expected range. These outlier readings are fairly common, and perhaps a software update can address these.

Apple Watch heart rate reading

OK, so you’ve let Apple Watch get another reading or four, and the heart rate is still way off? Why?

Be Sure the Apple Watch Band Has a Snug Fit

The most common cause of Apple Watch providing inaccurate heart rate readings appears to be due to the fit of the Watch band itself. A loosely fitting band that moves around at all, or that has notable gaps between the Watch and the skin, can easily cause an inaccurate reading. For the most accurate heart rate readings, you will want to be sure you’re wearing the Apple Watch fairly snug against your skin, which is a bit easier with the Apple Watch Sport bands and various bands with magnetic latches rather than some of the other bands, particularly the link bracelet. If you don’t have an Apple Watch Sport band, you can get a surprisingly good quality knock-off Apple Watch Sport band from Amazon for considerably cheaper than what you’d pay at Apple for an ‘official’ plastic band. Whatever band you use, just be sure it fits snug for the best results.

Apple Watch models

Check for Grime on Skin or Other Sensor Obstructions

Another frequent reason why Apple Watch may offer inaccurate readings is if the Apple Watch light sensors on the back of the device are obstructed, whether it’s grime, heavy dirt, film, undried lotions, or sunblock. From personal experience, certain brands (maybe types?) of sunblock can cause the Apple Watch heart rate reading to be way off, so if you exercise with the Apple Watch outdoors and wear sunblock, you’ll want to be mindful of that being a possible cause of an inaccurate hear rate reading. This seems to be particularly true with the greasier sunblock types that are sort of shiny on application, typically found with waterproof varieties, whereas the sunblock creams that dry out and don’t leave the skin all shiny usually are fine.

Bottom of Apple Watch where sensors are for heart rate etc

A Bug? A Software Solution?

As hinted at earlier, it’s also possible that some software issues may cause the Apple Watch heart rate monitor to be inaccurate, so be sure you install WatchOS updates when they’re available for Apple Watch to get any potential bug fixes or improvements to the devices capabilities. For example, a future Apple Watch update could discard the very first heart rate glance reading which is typically the inaccurate one, and only show the accurate BPM after that.

For what it’s worth, I’ve tried resetting and erasing the Apple Watch to set it up as new again, and it didn’t make a difference in the heart rate reading ability, so unless the feature isn’t working at all for you, that troubleshooting step is likely to be fruitless.

Have you found Apple Watch heart rate monitor to be accurate? Do you experience occasional inaccuracies? Let us know in the comments if you have any tricks or experience with the heart rate reading feature.

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Posted by: Paul Horowitz in Apple Watch, Troubleshooting


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  1. Peter B says:

    Can’t recommend the SHIFT band from EdgeGear highly enough. My watch is a much more advanced ‘at hand’ personal digital solution because of it in so many ways, but one of the first things I noticed was how HR accuracy and consistency was improved.

  2. Douglas B says:

    I agree with your tips to make sure the sensor is clean and the watch is snug on your wrist. An additional tip I can provide is to position the watch above your wrist bone rather than on top of the wrist bone. This positions the watch sensor on soft tissue and as a result can obtain a better reading of the blood flow.

  3. MRR says:

    When I do aerobic exercise on a treadmill, bike or eliptical it is spot on as confirmed by the equipment’s monitor. When I’m doing free weights, body weight exercises or weight machines it is often totally off – often reading 40 – 50 bpm.

  4. OJ says:

    I have found that if you use the tighter setting on a band it’s pretty accurate but yes I agree you have to ignore the first one or two readings and it’s usually the third and later that are accurate. It’s also more accurate if you run it constantly from the Activity workout apps.

    The heart rate reader is one of the best reasons to have an Apple Watch. I’m surprised nobody has made a band or attachment for blood pressure yet.

  5. HAJ says:

    The Heart Rate Monitor on the Apple Watch just isn’t very good. Simple as that. It’s temperamental, at best. If you want accurate heart rate monitoring, look elsewhere.

    • Simon Bramley says:

      The Apple watch’s heart rate monitoring is actually very good, if this article is anything to go by

      • Sebastian Villarreal says:

        Keep your article. the monitor is crap. haven’t had consistent accurate reading in any exercise regimen i perform. I’m dying and it tells me HR of 59! PLEASE. It just sucks and I wish they would admit it and not advertise is an exercise monitor.

        • James Ball says:

          I’m with you Sebastian. Technically the sensor should perform well but I find that in practice, whenever I’m doing a hard training session and have worked up a good sweat the sensor fails. I can feel my heart rate is in the 150+ area and the watch is either getting it completely wrong or just not showing any data.

          I’ve tried tightening the band. I’ve tried wearing it on the inside of my wrist. I’ve even tried using anti perspirant on my wrist all without any luck.

          Basically it’s a good heart rate monitor so long as you don’t sweat.

  6. Sara says:

    I found that during exercise, sweat was causing my watch to slide around a lot, which caused bad HR readings. Not to mention probably not good for the life of the watch. I started wearing a wrist sweatband just above the watch to keep the sweat off. It has been a huge improvement in accuracy, the watch stays in place, and I am sure much better for my watch. And a little retro NBA look at the gym.

  7. Matt says:

    While doing weight training I’ve noticed my heart rate can jump as much as 160 bmp to 50. I use the Under Armour Record app while I’m working out. When I notice my bpm being too low I’ve tried opening the Apple heart rate app and it usually corrects it. It would be nice not to have to do that three or four times while I’m working out though.

    • DubbDee says:

      I use the Record app as well. I have two Apple watches that I use, switch off every other day. One seems to give very good results while I work out. The other one is very erratic during exercise. I could be huffing and puffing away and it says my rate is in the 60-70 bpm range. The next reading is double that rate then it drops back down. I too have opened the Apple HR app and it will jump up to the expect rate.

  8. Mike says:

    I got my AWS2 for Christmas and I’ve worked out with it many times…and I have to agree with HAJ……it works intermittently at best! If NOT AT ALL. I use it on a treadmill at a walking pace and it’s completely inaccurate. I haven’t even tried it in a pool yet so I’m sure that will be a big let down I’m hoping it can be fixed with a update. I wanted to leave a review with Apple itself couldn’t find anywhere to leave a product review.

  9. Dan says:

    Like others I am not very pleased as yet with the heart rate monitor especially when lifting weights. It almost always reads at 1/2 of actual heart rate. Not sure it is accurate while walking on the treadmill either as it seems to read low. I have the spot band and wear it tight.

    • Craig says:

      I have had a AW series 1 for over a year. When i do cardio, the heart rate accuracy is good. When i lift weight, the amount of movement at my wrist effects accuracy as also sweat and hair. If i keep my watch tight, a little above wrist bone, it may miss several minutes out of an hour of monitoring especially in something requiring a lot of movement like clean and press.

  10. Kandy says:

    Why does everyone assume that the off readings are and inaccuracy of the watch vs something wrong with your heart?
    I have also experienced during exercise high HR then a super low drop. One time I felt dizzy. The others fine. For example 210-35bpm I felt dizzy then. But the other times going from 160-80bpm and back up to 135bpm in a minute time span. Now after reading this article, my watch isn’t that tight, and I can see the green lights on the back while working out. I don’t have the sports band either. I have only had this watch for 5 days so, after I tighten it up, I guess we’ll see.

    • Ina Carlo says:

      If you suspect there may be something wrong with your heart, by all means call your doctor and don’t rely on your Apple Watch to confirm it! Heart health is serious, don’t take a risk.

  11. Clau says:

    Are there any apps to get better graphs or that remove those outliers? That’s the one thing I miss from my fitbit

  12. Williams says:

    I have used the Apple Watch 2 since Christmas Day and I’ve noticed that every time I workout I’ll glance at it and the heart rate isn’t showing and it looks as if it’s trying to get the heart rate. I swear a lot so I then pause my workout take off the watch and wipe it off then put back on. It immediately gives me a heart rate. Also when it jumps back and forth from like 142- 69 I’ll pause the workout for a bit then start again and it’ll give me an accurate hr. I love this watch but it’s so frustrating every time I workout and have to keep pausing to fix it. As much as we paid for it I’d expect it not to have issues. I use to have a Fitbit charge hr and that never was off.

  13. Chantel Griffin says:

    I have recently bought the Apple Watch series 2 Nike edition. My heart rate monitor does not seem to be working when I exercise. My heart rate is definitely up but when it logs my workout on my discovery app it logs as speed only with NO heart rate. How can this be? This is an intermittent problem. Is there an update to solve this problem? I’m on software version 3.0.3. Any assistance would help. This is so frustrating.

  14. Kim hansen says:

    I notice that when i go for a run it works fine for awhile. And than it gets faded? The number cant be seen? Or all of a sudden it sits at 170 or 190 and no way am i breathing like that.

  15. Teresa says:

    Just bought my AWS2-Nike Sunday. This is my second attempt at AW. Had to return my S1 after great frustration and failed intervention with Apple support. I bought this one Sunday and used it Monday and Tuesday having frustration with it registering my green circle. Working myself crazy on extended and repeated efforts. Deliberately bought AW when I had a week off to test it. So after power walking 3 miles and adding additional miles to try to get my 30 minute circle I sat and read this forum. I still only had 25 minutes on green circle although I had power walked with some hills for over 1 hr. I had no sunscreen on. No lotion on any part of my body since yesterday afternoon. And I am not a sweat-er. I could not turn my band on my wrist and it had good contact. So I tightened my band 1 notch, even though it was already tight by my standards, set a timer for 5 minutes and took off. Now, I DID run into a coyote pup face on and that startled me but that was all. When my timer went off, I got message that my green goal was done – 5 minutes.

    I am less concerned with knowing my heart rate constantly. I just don’t want to kill myself trying to accomplish a green circle.

    Because of the silly coyote I have to retest but it can wait til tomorrow.

  16. Craig says:

    When you are power walking, are you starting a workout? This increases the frequency of heart rate monitoring. It also constantly monitors your level of activity.

  17. Damian says:

    It would be more accurate surely if you could enter a more precise weight rather than just in kilograms.

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