Since the latest update 3.90 my calories are doubled. All the personel setting are the same, but calories with Garmin HR band are much higher. A new HR band gives the same result. So it must be the software.
Here's a little bump to this post to say that I have the same problem. Calculated calories are doubled when not using a power meter. Clearly incorrect.
I'm having the same problem. I use a speed meter and a heart rate monitor that come with my Garmin 920XT Tri Watch. I have no power meter. I used both devices during my ride and the 920XT recorded 391 calories while my Edge 1030 recorded 752 calories. This has been happening since I installed the software update version 4.0. Both devices use the same heart rate zones and max heart rate for cycling.
No difference in calorie count for when compering the different firmware's from 3.90 to 5.0. I'm not using power meter only Heart rate and cad sensors.
I don't know why Garmin keeps ignoring this issue. Calories are more than double of any reasonable value for me (I'm using HR strap & Cadence sensor but no Power Meter). For example I got 2,881 for 120 minutes ride. Strava calculated the same ride 1,274 Calories which is way more reasonable. I also don't now if it has a connection or not but rest heart rate keeps reseting itself to 30 BPMs and as much as I would love to have this value I'm not there (around 45-50). Maybe it has something to do with the way Garmin calculate the Calories. I also didn't see any place in Garmin Connect that allows you to change this value (only on the Edge 1030 itself). Hope Garmin would fix it as the latest firmware (5.00) is finally starting to look like a good progress towards more stable device.
Calories seem way out for me as well. Last night I rode 22 miles at an average speed of 9.8 miles with heart rate, cadence and speed sensors connected and it recorded 3047 calories. This seems miles out too me !
I have some direct correlations, and can say WHEN this broke I did two rides, same route (24 miles), same kit (Garmin HRT, speed and cadence sensors) within 10 days of each other (nothing in between, shameful !) and the 2nd ride is double the calories (1171 compared to the later 2215).....and since then, all rides have been around double the calorie value I would expect. Between 24 Feb 2018 and 4th March 2018, SOMETHING changed and assuming it was either firmware or software, but I am sure someone has a release schedule they can look at. For sure...I would "like" to consume 2200 calorie on a 24 mile ride, but that is NOT the case - I *know* that
