Hoes does one get this?

Every site I see seems to have a wide range of cals burned. Such as one site will list cals burned in a 1 hr game of basketball at 490 and another will list the same at 920.

Is there a more accurate way to get this information?

No, it's impossible for a website to give you an accurate amount of calolories burned. They are all averages or approximations. It all depends on how your body works, how hard you play, and a spew of many other factors that are involved.