calorie burned discrepency

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So I just rode the stationary bike for 30minutes, when I enter it in under stationary bike moderate effort for 30minutes it says I've burned 403 calories. My bike on the otherhand (Pro Form Series) says that i burned 141 calories. BIG DISCRECPENCY!!! I rode for 30min, at aprox. 12.5mph, and went 6.5 miles.. WHAT'S THE REAL ANSWER?!!?