There is no simple answer to such a question. The length of time that it will take to build muscle depends on a number of factors. The real question should be, how long will it take you as an individual to build muscle Mass.
First of all you need to figure out what your body type is. You will find that there are 3 body types which are typical, although there can be a crossing over to a certain extent.
How Long Does it Take to Build Muscle Mass For an EctomorphAn ectomorph is a person who is skinny and has small stringy muscles. Even if an ectomorph ets lots of food, gaining weight is still a challenge. It can take a long time for this type of body to build muscle.
The ectomorph needs to be careful not to overtrain. Calories are burned very quickly in this person, due to having a fast metabolism. A few pounds of weight can probably be lost just through a few coughs. The goal is to train heavy as possible, but to keep the workouts short. However weight training should only be performed twice a week. Keep away from cardio, get plenty of sleep and eat lots of food. It is vital to save calories.
How Long Does it Take to Build Muscle Mass For an EndomorphAn endomorph is a person of a big build, wide hips, prone to store fat, and has a slow metabolism. Gaining muscle on this type of body is not that great a challenge. The real problem lies in fat storage due to having a slow metabolism. A layer of fat will probably cover any gain in muscle.
The endomorph can train with weights around 3 times a week. Endomorphs also need to add cardio workouts to their training. This person will have to watch calorie intake as well. It is important to have a diet based on more fresh foods.
How Long Does it Take to Build Muscle Mass For a MesomorphA mesomorph has a body that is built to gain muscle easily. The body frame typically consists of narrow hips, wide shoulders, slim waist, and a generally athletic look. Gaining muscle will not be a problem for this person.
There is not much else to say about mesomorphs, apart from that they are the envy of everybody else. They have the best bodies to build muscles.
In most cases many of us fall in between the 3 body types to a certain extent. Building muscle is possible for most of us, regardless of body type. It may be harder for some people than others, but in all cases it is possible. Your training should be geared towards your body type.
How long will it take to build muscle mass? Well that depends on what nature gave you, and picking the right bodybuilding program.