Accurate determination of calories burned can only be accomplished by individual physiological testing.
The next best thing is to use an ergometer. Beware, some bikes incorrectly claim to be ergometers but they do not measure power. Real ergometers measure how much power is put into pedaling the bike. This is needed for a reasonably accurate estimate of calories burned. For a more accurate calorie calculation, you would need to take into account the physical properties of the person using the bike. Many ergometers don't do this.
Measuring power is expensive. Adding this capability to a pedal exerciser would raise its cost by hundreds of dollars. Because of this, the calories burned estimates can be off by a factor of 10. The calorie numbers on the display are only close if the resistance is set to maximum. This is true for all pedal exercisers, including the MagneTrainer.
We have developed an Online Calorie Calculator that effectively turns the MagneTrainer into an ergometer. In addition, this program takes into account physical properties of the person using the bike.
If you prefer an automated solution, you may want to consider the MagneTrainer PC Interface.
The MagneTrainer PC interface connects your bike to a Windows computer and automatically logs your calories burned.
"I am immensely pleased with both the build quality and the resistance. This will provide good solid exercise when couch-bound. Great for those of us who don't like to go out in the cold and/or have small apartments."