Calorie Equation / Calculation

[Echilon]

Is there an accepted standard for calculating the calories burned spent doing an activity for a known length of time? There are various lookup tables and calculators which I've found, but it seems a tad fluffy and the values always seem subtly off. Eg: The tables at http://www.shapefit.com/calories.html don't match those at http://www.changingshape.com/calculator ... es-burned/.

Is there a way I can deduce a multiplier from the values in the first link so I can get some sort of equation for calculating calories burned as a product of a known body weight and exercise time?

[Boss Man]

I put something into both and got similar figures. The Shapefit one is based on 3 different weights, but unlike the other one is not customisable.

The other one however lacks the options of the Shapefit one, but you could use the Shapefit one to read between the lines and you should get a ballpark amount, based on the weight you choose, by working off the Shapefit figures.

The thing is though, most of these things will have been originally based on some kind of electronic measuring system, so how accurate they can be is debateable, which is something to be mindful of.