Sitting is among the lowest calorie-burning activities, but the more active you are in a sitting position, the more calories you will burn.
CaloriesperHour.com's activity calculator divides sitting into several categories. For a 150-lb. person, sitting quietly burns 68 calories per hour, sitting while talking, spectating at a sports event or doing light work burns 102 calories per hour and sitting while doing moderate work burns 170 calories per hour.
The heavier you are, the more calories you will burn in a given length of sitting time. For example, in the categories listed above, a 200-lb. person burns 91, 136 and 221 calories per hour, respectively.
Calorie-burning rates for each type of activity are highly variable among individuals due to other factors besides weight, such as fitness level, age, sex and health status. Consider all figures estimates rather than hard numbers.