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Charge vs Inspire - Numbers Off?

NysportsredNysportsred Posts: 207Member Member Posts: 207Member Member
I had a Fitbit charge that broke so I got the Fitbit inspire. I have done similar workouts using the two and have found that although my information in the app has remained the same the two Fitbit’s are not close at all when comparing the workouts.

Example. On the treadmill I used a 55 minute workout I recorded on the charge and did the same with the inspire to gauge how close the numbers were. Exercise equipment I know will 90% of the time be very off when compared to heart rate monitors, calorie counters Fitbit’s, etc., but I have this this a few times with similar results. As an example:

Treadmill – 55 minutes, 2.85 miles, 413 calories
Charge - 55 minutes, 2.41 miles, 440 calories
Inspire – 55 minutes, 1.98 miles, 496 calories

I wear the inspire the same way, same hand, info o the app again has not changed. Anyone know why the numbers are so off? Is the inspire likely over counting or was the charge under counting? Not too sure what the difference in the models are.


  • heybalesheybales Posts: 16,883Member Member Posts: 16,883Member Member
    Be curious if they saw the same number of steps.

    Because ultimately it's the impact of the step that creates a distance, and then distance and pace and mass is calories.

    But since yours went backwards - it's obviously using HR-based calorie burn formula, not more accurate Step-based.

    So what was the avgHR for the walk where each device was worn?

    And if the distance is that far off, either the treadmill hasn't been calibrated in awhile - or your'd greatly benefit from getting your stride length setting manually set.
    Walk 1 mile at 2 mph. Create an Activity Record for that chunk of time if no workout created - and see how many steps done for that mile.
    Then do the math for 5280 ft / steps, convert decimal part to decimal inches correctly.

    Now the device can have increased accuracy for workouts and the likely greater number of daily activity steps.
    And the daily steps aren't going to use HR-based calorie burn, so much benefit to daily calories though that wasn't your point.
  • NysportsredNysportsred Posts: 207Member Member Posts: 207Member Member
    Sorry I just saw this. MFP randomly gives me notifications then doesn’t. The charge stopped working before I could test much further :(
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