I'm not sure if this belongs here or in "Off Topic".
I'm working on a character whose parents are of Captain-equivalent rank. The character's father was a Captain in the U.S. Army when he retired while the character's mother is a Flight Lieutenant in the Royal Air Force. How old should the Officers be?
Edit: What is/are the military courtesy(ies) in the U.K.? I know the courtesies in the States are "Sir", for men, and "Ma'am", for women, however, "Sir" is used for knights in the U.K.
Regarding the original question, it might help to know the setting. Examples some people gave (like the famous and controversial Hackworth) are the exceptions to the rule which occurred in a different period than now. I think I even remember hearing about a 19 year old general in the Civil War, but he wouldn't make a very believable character in a modern setting.
Yes, there are exceptions, but if you want the standard way things are, you can go something like this:
A character graduated high school at 18 and went directly to college, where he spent four years earning a bachelor's degree. He is then commissioned into the Army as a Second Lieutenant. Then figure two years to make First Lieutenant, another couple or three years for Captain, then the promotions slow down considerably.
In this case, he probably wouldn't retire as a captain (in a normal retirement situation.) In the U.S. military, people can retire after 20 years service. If he hasn't been promoted past captain in 20 years, there's a problem, and he would probably not last that long in the Army. It is also possible to stay past 20 years, up to 30. Yes, there are exceptions, but they're rare.
The most likely way to "retire" with less than 20 years service is a medical retirement. In that case, he could be a retired captain.
The most likely way for someone to be a retired captain is for him to have taken a different path than the four years of college then get commissioned at 22 years of age. He could have enlisted (at age 18) and served for several years, then receive a commission through one of many enlisted commissioning programs in the various services. That way, if he was commissioned as a second lieutenant at 30 years of age, he would probably make captain at age 34, and retired a captain at 38.
As I said, there are exceptions, loopholes, etc, but this is what you would most likely encounter in the modern U.S. system.
Oh, another note which someone brought up earlier ... the names of equivalent ranks are different in the Army and the Navy. An army captain is the same rank as a Navy lieutenant, while a Navy captain is equal to an Army colonel. So, if you've seen references to a "retired captain" it might very well have been a Navy captain.
Hope this helps, and I'd be happy to answer any other military related questions. Unfortunately, my knowledge of the RAF is limited to what I can look up on Wikipedia, and the British education system is a mystery to me (even with