Calorie counts Garmin 305 vs 910

The 910xt uses a different formula to calculate calories (includes your HR). The 305's calorie calculation was only based on distance and your weight/gender. This supposedly makes the 910xt more accurate, but in reality I'm not sure how accurate either is. The real number might be somewhere between.

My 910 calorie count was about half of the 305 count until I set up my weight, height, heart rate zones, set my activity class and chose that I was a lifetime athlete. I'm not sure which one made the different. The 910 is still lower than then 305 but seems reasonable now.

I have the opposite problem, in that my Edge 500 gives me readings that seem fairly accurate, but my 910 gives me ridiculously high readings. It's kind of annoying, since I make a point of wearing my HRM and my profile information is up to date, so I'm not sure why it seems to think I'm burning so many calories. For example, my Edge will give me around 400 calories for an hour on the trainer, and the 910 will give me over 700. I wish!

Sorry I can't be of any help!

If I wear the HRM the 910 seems pretty accurate (been tracking calories about a year), although I do discount it a little.  Without the HRM it's way high, commonly take 25-30% off

I find differences between BT and Garmin Connect. For example this is the data for my last long bike ride this past Saturday:

- Distance: 64.59
- Time: 3:00:31
- Avg. Speed: 21.5 mph
- Calories burned according to BT: 3,371
- Calories burned according to Garmin Connect: 1,456

Any of you know which one is correct and what the problem may be? I though BT will upload the data straight from my Garmin 910...