Is it me or is it Fitbit

[YachatsMike]

I just finished a 1.5 mile walk in 25 minutes.  My Inspire 3 says my average HR was 88 bpm.  I make this walk often and I usually get between 105 and 110.  For other exercises, I'll sometimes see short  (5 minutes or so) jumps in my heart rate of about 20 beats, sometimes higher, sometimes lower.

Is this my real heart rate or a Fitbit measurement error?  How do I tell?  How do I make sure I get an accurate reading?  (I already follow the instructions about placement of the tracker and tightness of the wrist band,)

Any ideas?

[JohnnyRow]

For one thing, don't just look at your avg heart rate.  Look at the heart rate chart of your workout.  Was it often around 105 or 110 with big drops that affected the average, or was it lower all the time?

[YachatsMike]

I always look at the HR graphs.  The 88 bpm walk was a low but smooth curve.  The excursions during other exercises sharp jumps up or down and, after a few minutes, a sharp return to a more rational number.

[Dave369]

I pay no attention to Fitbit Exercise HR.  I find the resting heart rate to be accurate as measured by BP monitors at the doctor's office, my pulse oximeter that I have and my own manual measurement. Exercise heart rate on Fitbit appears to be more of a measurement of step count to me or at times something else but not my exercise HR.  If I am walking fast and on an incline on a treadmill, my exercise HR will show in the 120 bpm range on Fitbit whereas the hand grip sensors on the treadmill will show 89 or 95.  A significant difference and my HR is usually lower than most people.  This has always been the case for me.  Fitbit resting HR is spot on, exercise HR measures my step count or perhaps something else but not often accurate. 

[Triletics]

@YachatsMike it depends which Fitbit model you use as they seem to provide different level of accuracy. For me, Sense and Sense 2 always reported inflated HR during walking but lower than real HR during running. Charge 6 reports correct HR during walking but horribly fails during running when it mistakes my steps for HR. Only way to know for sure is comparing data against chest strap.