Calorie measurement

I’m curious what method is used to calculate calories burned?

When I download the FIT files, and upload to Garmin/TrainingPeaks I noticed Connect assumes I used a Garmin Edge 500 (which I think uses 1st Gen firstbeat algorithm).

Every application estimates calories to a degree. Strava has their own calculations and we do as well (based off wattage and human efficiency). They will most likely become more accurate over time.

My calorie calculations seem off by about 200% from strava’s gps calculations and and the online calculators I’ve used in the past. what gives?

I’m 220lbs I ride 15 miles over 1 hour.

Zwift: ~300 calories

Strava: ~950 calories 998 calories


It’s the same for me…way off.

60 minutes, 145 avg bpm at 142 lbs (5 ft 6)

Zwift = 560 ish
Most calorie calculators = 860 ish

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For me it’s the same … 4wk FTP booster - 80% FTP / 50 min

Garmin Forerunner 935 - 660 kcal

Zwift with Tacx Neo - 356 kcal 

Too much of a difference for 2-3 high-end priced products :wink:

Makes the value rather obsolet. 

Does anyone have an idea which to trust more?