Average ages per rank in US Military

Here's the average time it takes to be promoted:

Private (E-2) - 6 months Private First Class (E-3) - 1 year Specialist/Corporal (E-4) - 18 months Sergeant (E-5) - 4.2 years Staff Sergeant (E-6) - 8.5 years Sergeant First Class (E-7) - 13.6 years Master Sergeant/First Sergeant (E-8) - 17 years Sergeant Major (E-9) - 20.8 years

So, assuming you're 18 when you join, just add that much time, and that's your average age per rank.

Or if you're talking officer, start at say age 23, and then add: O-2: 18 months O-3: 4 years O-4: 10 years O-5: 16 years O-6: 22 years

Anything at or above O-7 is competitive, so there's no average time avaiable

Source(s):
Article:
 * http://answers.yahoo.com/question/index?qid=20080711111258AA49D1p

The ENLISTED promotion chart came from:
 * http://usmilitary.about.com/cs/armypromotions/a/armypromotions_5.htm

The OFFICER chart came from:
 * http://usmilitary.about.com/od/promotions/l/blofficerprom.htm