I have no idea how much it is, but I would not count it anyway. The problem with factoring it in is that you might use it as an excuse not to do your regular exercise. I've seen a lot of people who have where they're on their feet all day and when it comes time to exercise, they say they don't really need it cause they've been walking around all day anyway. Just think of it as bonus exercise.
Also don't pay attention to the readout on a treadmill or other equipment. The people who program those displays make assumptions about the average height, age, build, etc. about a person. Usually the number displayed is higher than what you really burned.