Ionic distance accuracy

[chipcinnati]

I have a 2-year-old Ionic, which I have really enjoyed.  I've always understood that Ionic combines foot-step distance and GPS to track the overall distance of my outdoor runs.  I've found that my Ionic always undercounts my distance by about 1-2%, or about 0.01 or 0.02 every mile. I can live with that, especially because when I race, my undercounting Ionic times will come out faster in the official race results.

As I've recently become more focused on varying speeds in my training, these slight deviations have become more glaring.  When I do speedwork (6-7 min/mile,) my Ionic can never get the pace down to where I expect it to be.  When I run a 5k, the gap between Ionic's estimate of distance and the official race distance is far more than the 1-2% distance.  It's not so noticeable when I run longer races (13.1 for instance,) since my 13.1 pace is closer to my typical run pace.

I allow Fitbit to adjust my stride length automatically, but when I purposefully run different paces (speedwork vs long run pace,) then I purposefully run different strides.  

Is this the best I'm going to get with Fitbit?  With a straight-GPS watch (no stride length) like a Garmin, the only factor is GPS estimation of my distance, no matter how fast I'm running.

Thank you!

Moderator edit: Subject for clarity 

[RicardoFitbit]

Hi @chipcinnati, welcome to the Community Forums!

I appreciate the information that was shared in your post. If you feel that your step count and distance are inaccurate, confirm the following are correct in the Fitbit app:

• Your wrist settings (For more information, see Does the wrist I wear my device on affect accuracy?)
• Your height (For more information, see How do I manage my Fitbit profile?)

Since we use height to estimate your walking and running stride lengths, you may want to measure and manually adjust these values if your legs are longer or shorter than average. For more information, see How do I measure and adjust stride length for my Fitbit device?

Sometimes, when you start walking, your steps may not update on your device right away. After about 10-15 continuous steps, you'll notice the steps catch up and start updating in real time with each step you take. Also, I recommend you to restart your Ionic device to refresh its performance.

Let me know if you have any additional questions.

[chipcinnati]

Thanks for the reply, Ricardo.  

My wrist is set to "Dominant" (left-handed) and my height is correctly set at 6-0.

I have tried setting a manual stride length before, but that has unintended consequences as well, so I just leave it as "set automatically."

I don't think there's any way Fitbit is automatically gauging my stride length as I change speeds when I run.  Frequently in my workouts, I'll start out slow and then increase speed through the workout.  When I increase speed, frequently I'm lengthening my stride, which allows me to cover more distance.  There's a difference in stride length when I'm sprinting versus when I'm doing a long run.  That's why I asked my original question, because I can tell that Fitbit struggles more to keep an accurate count of distance when I'm running fast, like in sprints or 5k's.  Sometimes I wish I could just shut off the step-counter element of the distance estimation and go with GPS-only like Garmin.  Given that I run a lot of different speeds in my outdoor running, I think I would get more accuracy that way.