Hiking- calorie consumption question?

The database entry for "hiking, cross-country", I believe, assumes that you start and finish in the same location and experience both uphill and downhill stretches on your hike or you are hiking on level ground and that you are not carrying a pack. There are 2 other entries in the database for hiking uphill, carrying a load (pack). One for a daypack (<10 lbs) and one for a backpack (>10 lbs), is my assumption. All 3 are just estimates, of course, and don't consider other factors such as the roughness or steepness of the terrain, stream crossings, traversing snowfields, etc. But if you compare the calories burned per minute hiking with, say, walking at 3 mph, you'll see that it credits you with more calories burned per minute by hiking, than by walking. (3 mph is about the pace my wife and I hike at unless we're having to do some of the tougher stuff like crossing a boulder field, stream, or snowfield.)