How many inches can a growth spurt add to your height?
The period of time during adolescence that we call a growth spurt is when the rate at which you are growing accelerates over your previous growth. From the time you were just a baby until now, you have always been growing. On average you have grown about 3 inches a year before five and about 2-1/4 inches per year between five and puberty. But during the growth spurt, the average boy will add 3-3/4 inches per year. For a few boys it can reach as high as 4-3/4 inches per year.
Again, using averages, most boys will add about twelve inches to their height during adolescence (from stage 2 to stage 5). About six of these inches will be added during your growth spurt during stage 3. Studies show that boys who reach puberty later in their teenage years generally end up taller because they start from a higher point [Yehuda Limony, "Age of onset of a normally timed pubertal growth spurt affects the final height of children", Pediatric Research].
Just remember that all of these numbers are averages and I have been speaking in generalities. Genetics and proper nutrition strongly effect your final height. Your genes set your maximum height and your health determines whether you reach your full potential height.