fitness and calories

I am practicing fitness every weekend. The problem is I never know how much calories I have burned. I do walking and running on Sunday. I was wondering is there is some rule of how much calories man can burn in min or hour?

You can find out how many calories you've burned by putting in your weight and number of miles run/walk. I read that researchers found that the people who walked and run burned the same number of calories at 5 mph, although running calories were consistently higher than walking calories at speeds below 5 mph, walking calories increased faster with speed than running calories. I don’t know what you consider under fitness but it seems that to lose one U.S. pound (.45 kg) you must burn 3,500 more calories than you take in.