Is there a rough calculation for number of calories required to maintain a certain weight?

I know that people vary in metabolism and amount of exercise, so any calculation would have to be only an approximation. The formula I came across is that it takes 12 times body weight in calories to maintain that weight. This seems a bit high.

Such a calculation could be used for dieting. Suppose a person is very overweight. That would mean that the person could start off taking in a fairly large number of calories and still manage to lose weight. As the person loses weight, the calorie intake would have to decrease. This seems to make more sense than for such a person to start right away with a 1500 calorie diet.