Heart rate difference between workout and regular mode

[Womple]

I have been using my Fitbit for about 6 months now and I have noticed a difference between workout mode and regular mode with heart rate displays. 

I am trying to keep my heart rate between 100-140 for my current fitness goals, and so the workout function is good for this. However, sometimes I have forgotten to start the workout on my fitbit and will be mid exercise where I know I should be between 130-140, look down at my fitbit display and it will report my HB to be around 85 or 90. When I start my workout mode on my fitbit it will stay the same for about 5-10 seconds and then spike to where I expect it to be. I have used separate monitors to verify my heart rate and it seems the fitbit is fairly accurate when in workout mode, but completely unreliable during normal mode.

Does anyone know why this would be and if this is a "feature not a bug" type deal?

[Marrrmaduke · Accepted solution]

@Womple It's because of different sampling intervals of your HR measurements. In the workout mode it's being measured each 2 seconds (I think don't quote me on that) whereas in a "regular" mode it's more like 10 seconds (or 5?). I don't remember. 😄