Hello @tomaszkorczak 

Thanks for posting about this.

Strava shows Calories as they were provided to us by upload partners. If no value is sent, or you record with the Strava mobile app, we use our own calculations. At this time, Strava only performs a calorie calculation on a ride, run, walk, and hike activities. All other activity types will not display calories unless the upload partner includes the data with the activity upload.

Please let us know if you have any further questions.