Using calories burned on the machine or in the database?

Almond_joyz

I use ellipticals and bike machines at the local Y and have noticed that the calories burned differs widely between the two. When I'm at the Y, I put in my age and weight to get the right calories, but then get different numbers when I enter the exercise on the website.
I tend to use the number from the machine because I feel it's a little more accurate. Am I cheating by using the larger number that the website gives me?