Numbers are always going to be off because each person is different and depending on your activity you could use a lot more calories and require a lot more too. Sure you can average but that's never really that accurate.

I suggest keeping track of what you eat exactly for a month or two 6 would be better and then figuring out what you need yourself.

I know when I am chopping, stacking wood and shoveling snow all in one day I eat a LOT more calories than a normal day.

Recently I had. Hot cereal w/bread for breakfast, tuna/egg sandwich for lunch with cheetohs, 4 pop-starts spaced apart during the day as snacks, an apple, then a bean burrito (large) and 2 tacos for dinner, and a snack later on. I've found pop-tarts to be one of if not the only readily available energy source for fast refill and fast acting that don't make me tired after an hour or two that sometimes occurs with a candy bar. I weight approx 150lbs and am under 6' tall. I'd imagine this type of meal is not standard on a food calculator but in a survival situation I could see myself doing a LOT more manual labor than if I had gas and machinery to help.