When using Xert, the app shows a higher calorie burn than Garmin connect, which is more accurate? Xert usually shows the calorie burn at 110% of the kilojoules (work)
I think here applies the same answer as witb 2 power meters…the higher one is always right 
But seriously I think this is a very tricky one, I m sure Zwift and Strava show different values as well.
The calorie burn depends on what efficiency the company uses to convert from kilojoules to calories. Everyone is different and can vary from 18% to 25%. The software has no way of knowing what your particular efficiency is. Xert uses 22% I believe. Trainer road uses roughly 25% ie straight conversion of kJ’s to Kcals. If you are particularly anaerobic ie a sprinter it is likely I understand that you will be at the bottom of of the range and vice versa if you are slow twitch dominant. I had a metabolic test done pre covid which showed I was at about 19% at the power outputs I normally cycle at. It changes with power output. Hope this helps.
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