Your elliptical console’s calorie display is to be used as a reference only to monitor improvement from workout to workout. Calorie count is determined not only by the workout program you have chosen (time, resistance, speed), but also by the user profile information you may have entered into your machine (weight, age, height).
No exercise machine can give you an exact calorie count because there are too many factors which determine exact calorie burn for any particular person. Even if someone is the exact same body weight, age and height, their calorie burn may be very different from yours.
IMPORTANT: Always consult your physician before participating in any exercise program or regimen.