A calorie, also known as a kcal, is a measurement of the usable energy that is contained in food and is needed to fuel physical activity. Half a kilo (one pound) of fat holds the equivalent of 3,500 calories. So to lose a half Kilo (a pound), you must do enough activity, or reduce your consumption by enough, to force your body to burn 3,500 calories of fat. Standing does burn more calories than sitting. But the exact amount of kcals used for each activity depends on a person's gender, weight, and length of time performed.
According to an energy expenditure chart in the book "Exercise Physiology," the calories burnt by males and females will differ for specific activities. For standing, men tend to burn a 1/10 to 2/10 of a calorie more than women per minute. So a 59kg (130-pounds or 9st 4lb) woman burns 1.5 calories per minute standing still, but a 59kg (130-pounds or 9st 4lb) man burns 1.6 calories. A 79kg (203-pound or 14st 7lb) female burns 2.3 kcals per minute versus 2.5 kcals for the same sized male.
The amount a person weighs affects calories used for all activities, including sitting and standing. The more a person weighs, the more calories will be used for each activity. A 68kg (150-pound or 10st 10lb) person will spend 84 calories sitting for an hour. A 77kg (170-pound or 12st 2lb) person will use 96 instead.
Length of activity
According to the third edition of "Exercise Physiology," calories are determined per minute of activity. More time means more calories used. For an hour of quiet sitting, 66 to 126 calories are spent (depending on body weight). Standing still for an hour burns between 78 and 156 calories.
Sitting vs. standing
Quiet sitting burns fewer calories than standing still. If you sit for 30 minutes, you will burn 33 to 63 calories (for 50kg up to 98kg individuals or 110-lb. up to 216-lb.). But standing for 30 minutes means burning 39 to 78 calories. So standing yields around 12 to 30 more calories per hour. For a full day of work (8 hours), standing might mean 96-240 more kcals used.
Sitting and standing vs. walking
For a 68kg (150-pound or 10st 10lb), he would burn 84 kcals sitting; 108 standing; and 324 walking for an hour. Normal walking on a pavement surface uses between 240 to 468 calories per hour. Sitting burns between 66 to 126 for the same amount of time. Standing expends between 84 to 156 per hour.