Cosign on what CDB said.
You can't get down to the gram on calories anyway, so don't try. All calorie measurements are estimations, and so is any calculation you do on your BMR. Personally, I recommend starting at 18 x bodyweight in calories minimum and go from there. As CDB said, add more food until you are gaining weight. Notice he said weight not muscle. Go by the scale. If you are not adding a couple pounds a week then eat more. And realize that the more weight you gain, you will require proportionally more calories.
I tell people that if they are not at least slowly gaining a layer of fat as they bulk, then they are not eating enough to build any significant muscle. People are so afraid of overeating and getting fat, but in reality, they always end up undereating and as a result, staying tiny and weak.