I walk, on average, a 15 minute mile and on flat terrain. I weight 150 lbs and I'm about 5' 7" with a medium build.
I'm trying to manage my overall health and want to ensure my exercise is balancing my food intake properly.
Here is one calorie burn calculator (Shapesense.com) for walking.
I walk a lot and I have a walking tracker with calorie counting on the phone but I never use it. Calories burnt just don't tell me anything. I use the holes on my belt as a measure, seriously.
Walking alone is not that great to lose calories, unless you walk really a lot. A relatively easy way is to stop eating some types of food, for example all dairy or all sweats and such, and to eat whole-grain bread and vegetables, which prevents food craving a bit.