Heart rate monitor not accurate during exercise

[Admroe]

Hi, so I bought my first ever Fitbit  (Charge 3) as a way to help me measure and monitor my level of activity (mainly at the gym). I need to keep my heart rate at a constant rate for fat burning.

Wore it today for the first time at the gym and it just sat at no more than 80bpm. I checked using the gym monitor and I was up at 140bpm. How can something called a Fitbit that is supposed to be about monitoring levels of activity be so inaccurate? 

PS: after about 30-40 minutes of session it suddenly shot up to 150bpm.

I’m hoping this was a one off and net time it is more accurate otherwise I think I’ll have to be emailing Fitbit directly.

Is this a common issue and if so has anyone found a way to increase accuracy?

thanks

[Lufalulz]

Since this is your first Fitbit, make sure you're wearing it properly.

Check Fitbit's guidelines here.

Hope it gets better!

[pilv13]

After you've checked that you're wearing the tracker correctly could you report back here and let us know whether it's still giving you false readings?

[BrianDil]

Just finished my first workout with the Charge 3 and had inaccurate heart rate as well. I was on an elliptical for 30 mins and the machine showed 170 but my Charge 3 never went past 125. I previously had a Charge 2 which worked fine. 

[Admroe]

Will let you know how I get on later in the week. 

[HikeWithDogs]

I had the same issue today. Charge 3 was reading 130 bpm but when I stopped and took my pulse it was over 160.

I just bought this because I wanted to add heart rate tracking. I was previously very happy with my Fitbit One for steps and floors. When the Charge 3 arrived yesterday, I went for a brisk uphill walk and it seemed to be correct reading around 160 on the hills. I stopped to take my pulse a few times and my measurement matched the Charge's reading.

Today I was climbing stairs and the Charge displayed 130 most of the time. Finally I began stopping every 10 floors or so to take my pulse and it was over 160 every time, while the tracker stayed at 130. Yesterday I had it on the top of my right wrist. Today it was initially on the top of my left. I tried the top and bottom of both wrists and finally at the end of my session, it briefly read around 160.

I've been wearing it snugly, an inch or two above my wrist bone. It seems to have good contact because it's leaving a slightly raised oval on my skin, from where the charging connector is indented a little on the back of the watch.

What gives? My goal in monitoring my heart rate was to avoid overexerting myself, so it was useless to me today.

[pilv13]

From your reports the heart rate monitoring on the Charge 3 sounds positively dangerous to use.

The HR is also one of the main reasons why I ordered the device.

[SunsetRunner]

One of the reasons I purchased this Charge 3 was to monitor my heart rate.  Today I was sitting most of the day and my heart rate on the FitBit was 112-132.  I have a blood pressure machine which I would periodically check and the pulse rate was more 75-85.  This is a huge discrepancy and I am wondering if there is something wrong with the Charge 3 or settings?  If not, I am going to return the FitBit.  This is the first FitBit product I have purchased and along with the text messages not showing up when I would receive texts today, I am thinking that this particular watch is not functioning correctly.  I also noticed that my Iphone is being drained of battery life.  Not happy - any help?

[JuanJoFitbit]

@SunsetRunner It's great to see you in our Fitbit Community! Let me go ahead and find a solution for the wrong heart rate numbers that you are getting from your Charge 3. If you haven't done so, please restart your tracker as described in this help article. After this, monitor your resting heart rate for the next 24 hours. In the meantime, make sure that your tracker is not too tight on your wrist.

Keep me posted on the outcome! 

[HikeWithDogs]

Another symptom to report on my Charge 3 that was reading 130 bpm instead of 160:

The first night I wore it to bed, it made a colorful graph of stages of sleep (awake, REM, light, deep). Last night was the second night, and it made a boring graph that only showed awake, asleep, and restless. Last night's graph looks the same as the graphs it would make when I wore my Fitbit One to bed (using its sleep wristband). Both nights, I went in the app to click "Begin Sleep Now" then "I'm Awake" in the morning. Why would it record a different type of data on different nights?

I'm adding it to this thread because I wonder if it's related to not getting heart rate data. But I would think if were moving around the second night and not getting a good heart rate reading, it would still make the same kind of graph with the best data it could detect.

My One is sitting in a different room on a table, not moving, so I don't think it's interfering.

[SunsetRunner]

My Charge 2 would intermittently display basic sleep data, it's nothing to be concerned about

[Blackish]

I checked the Charge3 heartrate vs. my Forerunner 935 during the day and a running excercise (12k). It was spot on vs. the Garmin. The Charge3 picked up intervals without any lag and was always within 1 or 2 beats of my Garmin. Based on my first day I am really happy with the Charge3 heart rate monitor!

PS. Placement on the wrist (on the arm, above the wristbone, not too tight or too loose) is key to the accuracy of the heart rate readings, YMMV.

[HikeWithDogs]

Yesterday I had the opportunity to compare the Charge 3's heart rate measurements to an EKG stress test. This time it was pretty close, though it lagged 5-15 seconds in detecting changes vs. the EKG. So the performance yesterday was ok, different from the problem I had the day before yesterday where it read 30 bpm low for almost my entire workout.

One difference is that I left the strap one notch looser yesterday at the same position I wear it throughout the day. Before that I had made it one notch tighter while working out, per the instructions. Yesterday I just wedged it another inch higher up my wrist, which worked fine on the treadmill but may not work if my arms are swinging. I'll have to see how reliable it can be. At least now I know to be suspicious of it if it seems way off and to check my pulse for safety.

Last night it reported only basic sleep data again. Is that related to heart rate monitoring? When I woke up this morning it still had good contact with my wrist, in a similar position to the stress test when it was reading correctly.

It also wouldn't connect via Bluetooth today until I restarted it...is it really true that it can only be restarted while it's plugged in? I don't want to have to carry the charging cable into the backcountry to get this thing working if it gives me trouble. I know syncing requires cell service but I've also had to restart it when it got stuck on the notifications and wouldn't let me swipe back to the clock face...I disabled notifications to avoid that happening again. My new $150 toy is gradually regressing to the same functions as my existing Fitbit One.

[Cwep2]

The HR readings don’t seem to be accurate during exercise for me. The readings didn’t go up when I was swimming pretty hard yesterday and I understand there are issues in water so put it down to that. 

Today I was on a rowing machine and again when I was working hard the HR readings didn’t go up much at all on the Fitbit, bUtah I was able to compare with a polar strap. See screenshots, Polar gives max 174, ave 152 and after the first minute it was above 130 the whole time. Fitbit showed max 112, average 101.

After the exercise the readings seemed to be much closer, it just seems not to be able to read the rate correctly when the heart rate is elevated. 

[HikeWithDogs]

Last night while reading in bed, I noticed my Charge 3 was reading over 100 for my heart rate. I measured it myself and it was 64. It had good contact with my wrist.

I'd like to hear from a Fitbit employee on whether they're testing this issue further or what.

I did figure out the sleep thing, I think - with the Charge 3 I think you have to *not* tell it you're going to sleep, just let it detect that itself. That must be what I did the first night I had it. It's what I did last night and it worked correctly this time.

[rs2018]

I had the same issue.  Charge 2 was spot on - Charge 3 no where near accurate during exercise - on elliptical for an hour with heart rate @SunsetRunner and the Charge 3 showed 95 the whole time.  Tried everything - tightening, moving up on wrist, making sure there was nothing obstructing the sensor (sweat,dirt, hair).  After a little bit of reading and investigation looks like the green light sensors (2 on the charge 2) are now only 1 (on the charge 3).  Simply turn over the fitbits and look at the green light and its obvious to see.  And to boot - intensity of the sensor looks to be alot less which is consistent with the battery life being extended on charge 3 model.  Looks like accuracy of heart rate sensor was traded for being able to advertise longer battery life and new features - I couldn't be more disappointed - one core reason I loved the charge 2 was because of the HR accuracy.  That's enough to turn a loyal customer into someone that is now looking at alternatives where still the core feature is accuracy of the heart rate.

[SunsetRunner]

You're not alone; this has been a problem, from what I've read. I LOVE my charge 2 because it consistently read my HR and I just thought the 3 would be Fitbit polishing up perfection, but it's the opposite. Last night I put both Charges on while I jogged. The 2 read my hr as 130 (as usual) but the 3 never got above 92. And yes, I moved both around and tried different placements. I have read in other reviews that this is a problem with the 3, so you're not alone in your observations!

[rs2018]

I really wanted to believe it was something I was doing but I tried everything imaginable over 3 days - couldn't rationalize why my older charge 2 had been accurate 99% over the last 2 years and the first 3 days of the charge 3 were no where near close (with the exact same workout).  Only thing I can think of is that many folks wouldn't notice unless they are consistently doing intense cardio workouts.  I was really looking forward to the new version - only real new feature I was looking for was the water resistance and the fact that it was new (I beat up my old charge 2 pretty bad but it was always accurate).  

[rs2018]

I returned mine yesterday ;-(.  My workout though was recorded accurately with my old charge 2 though 🙂 .  The extra battery life and water resistance would have been nice ..... ah well.  Let me know if you do find out anything more or are considering other alternatives.  My thinking with trying/staying with the 3 was why mess with something that works so well ... but not exactly how it turned out ..

[SunsetRunner]

Sorry to hear that... looks like I'm headed in that direction, too, and will just stick with my reliable Charge 2, but I'll let you know if anything changes. I'm going to give it a few more tries...