How Old Are Sixth Graders?

Sixth graders are 11-12 years old. They usually enter sixth grade at 11 years of age and turn 12 by the time they complete sixth grade. Some students though may not turn 12 until the summer months after sixth grade. 

Below is a table showing the ages for grade six, seven, and eight. These are considered middle school grades. 

I wrote this article and this one about middle school that will tell you more about it.