At rest the average 160 pound person* burns 69 calories an hour. That same 160 pound person burns 10 calories a minute while ascending a flight of stairs (no matter how many steps makeup the flight) and 7 calories a minute while descending.
That doesn’t seem like a lot. However, at 160 pounds, that person would have to run 1 mile to burn 100 calories. Therefore, if all things were equal, it would only take about 6 minutes of walking up and down stairs to burn an extra 100 calories a day.
*Remember the more lean body weight (muscle), younger the body and the quicker metabolism will burn more calories.