Inspire HR shows inaccurate calorie tracking for workouts

[Lrovis]

I recently got the Inspire HR. Last week, I went to 3 different HIIT classes that lasted 45 min each and the auto exercise feature tracked only about 20ish minutes for all of my workouts with very low (between 100-200 calories) per workout. This week, I tried manually tracking my HIIT workout, but it said I only burned about 250 calories. That still seems extremely low because these classes are expected to burn around 500+ calories, and a friend with the similar weight/height and level of effort during my workout class also uses a Fitbit and hers tracked well over 500 calories. I’m wondering if there’s a glitch with mine or if I’m not wearing it correctly? Any help would be greatly appreciated. 

Moderator edit: updated subject for clarity

[AlvaroFitbit]

@Lrovis A warm welcome to our Community! Sorry for the delay in my reply.

Let me help you with your calorie calculation for your activity. This will depend on the movement that your tracker detects and your heart rate. It could be that your friend had to do a higher effort to complete the activity thus granting her more calories. Still this is only a guess. If you think the activity isn't showing your real effort you can manually log the activity.

Also help your tracker improve the heart rate reading while doing these activities. I suggest you clean the back of your device with cotton and rubbing alcohol and restart it. Turn the heart rate off, save and sync then turn it on save and sync again. Finally check these tips to improve the heart rate reading on your device.  

Let me know how it goes.