How are calories estimated?
If you have a power meter Cadence uses that as it’s by far the most accurate way to estimate calorie burn. Otherwise, Cadence uses MET values with adjustments made for grade.
Cadence doesn’t currently calculate based on heart rate because testing has shown it to be wildly inaccurate, often producing numbers 30-50% more than expected. I’d rather err on the side of calculating too low.
Also, Cadence doesn’t send its calorie estimation to Strava when it syncs. This causes Strava to do its own calorie calculation on the data.
The reason I have it this way is because calorie calculation is pretty complicated. Unless you’re using a power meter on a bicycle, calorie calculations are an estimate at best. Big companies like Garmin actually license a calorie algorithm, and I’m guessing Strava and Apple do the same, or have their own algorithms. I figure with the number of engineers working at Strava, they’re going to provide a better calorie estimation than I can.