No Bones about Nutrition and Safety
So how much milk should you drink to meet your calcium need?
How much calcium you need depends on your age. 
CALCIUM REQUIREMENTS 
GROUP ADEQUATE INTAKES*  
(mg of calcium)
NUMBER OF MILK GROUP SERVINGS
CHILDREN    
1-3 years 500 3**
4-8 years 800 3
PRETEEN/TEENS    
9-18 years 1,300 4
ADULTS    
19-50 1,000 3
50+ 1,200 4
* Source: National Academy of Sciences, 1997  
** Serving sizes for children ages 1-3 are 2/3 of adult size.

Three to four glasses of milk per day will meet your body's need for calcium. 

And remember: cheese, yogurt, butter, cream, and ice cream are all excellent sources of calcium, riboflavin (B2) and protein too.  These products also all come from milk.  Since it takes about 10 pounds of milk to make one pound of cheddar cheese, cheese really is a nutrient-dense food.