The calculator below will figure out your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor Equation, which is a widely accepted equation used for calculating this number. Your BMR is the number of calories that your body burns at rest to do all of the things it needs to do to keep you alive and functioning properly. Your activity level is also factored in to estimate how many other calories you burn per day in addition to your BMR. The answer given is the total of the two and should be, for most people, a pretty close estimate of your daily calorie maintenance level.
Gains will differ from one individual to another depending on body size and level of experience in the gym. To make sure you're gaining muscle, not fat, don't just consider your scale weight. Instead, rely on what you see in the mirror and use a tape measure twice a month to keep track of your waist and hips (you don't want to gain there) as well as your biceps, chest and quads. Also, don't think that you have to gain a set amount of weight each and every week. "Your mass gain doesn't have to be uniform," Aceto explains. That means you can gain 1/2 pound one week and 1 1/2 the next, perhaps none the third week and still remain on course. "Expecting uniform gains ignores the intricate makeup of the body and the way it gains mass - or loses fat - which is by no means in linear fashion," adds Aceto.