I have two Garmin HR+ watches (same model) that give different results for calories burned - how do I know which is most accurate? Rest HR differs by 10 on each?

JoFo99 said:

My resting heart rate differs by 10 on both - why is this

Either because you do not always wear them both at the same time, or because each of them measures slightly different values.

JoFo99 said:

How do I know which is most accurate as calories burned during exercise differs by 200 calories per hour?

The one which measures the HR more accurately, and the one which records the more accurate Resting HR will be likely more accurate for Calories as well. However, you'd know for sure only if you make a calorimetric test in a lab.

Thank you.  Today I wore both at the same time, but still different results.  Its the VivoSmart HR+.  I counted my wrist pulse for 1 min and compared the reading to both watches and they both give the same HR reading.  I checked all other details, and the only thing that appears to be different is the Resting Heart Rate which differs at around 10 between the two watches so they are definitely measuring different values, but for running indoors (no GPS) on the spot for 1 hour gives 747 kcal burned on one, and only 500 kcal burned on the other, which is a really big difference.  I've compared all other readings including input height, weight, age etc, and the only thing that seems to differ is the resting heart rate reading.  I always wear on the same wrist.  Am at a loss as to why the readings are so different and which one I should rely on for an accurate reading. Thanks for replying to me, I appreciate your time and help.

JoFo99 said:

Today I wore both at the same time, but still different results

The Resting HR used for the calculation of Calories is a 7 days average Resting HR, so you would have to wear them simultaneously (and preferably on the same wrist) during 7 days and 7 nights (the Resting HR is mostly detected during the sleep). You can also disable the auto detection, and set the Resting HR manually. Not sure where it is in the settings of your watch, but on mine it is in the device menu » User Profile » Heart Rate & Power Zones » Heart Rate » Resting HR » Use Average » OFF

... besides the Resting HR, also other parameters may have influence on the Calories count - Max HR, body weight, height, age, gender, and depending on the device also the activity class, training history / training load / EPOC , and I may have forgotten a few other contributing factors. So if each of the watches uses different data, has different history, then the Calories calculation will certainly differ too.

Thank you so much - that really is so helpful. I will wear them both together for a week and see what happens.  I tried to see if I could sync them both together but that didn't really do anything.  Worst case scenario, I will reset them both back to default and wear both together for a week and see what happens then.  Thank you once again, I really appreciate you coming back to me.  If this works, I'll try and post as it may help others in the future too.  

BTW, do you have them associated both with the same Garmin Connect account, or each with an own one? Newer models sync data with each other using the feature Physio TrueUp (when on the same account). Vivosmart HR+ is not among them, so that feature won't help you even if they are both on the same account. However, only one of them can be the preferred Activity Tracker (newer models use the term Primary Wearable Device), so that can have also some impact on the data shown in your GC account - mostly it will come from the preferred tracker.

Thank you.  I will spend some time looking comparing the details between the two watches.  I appreciate your help and guidance.  Have a great week.