Well, I`d say more like 13...

i'd say private possibly joined near the age of 10 (and a half) so is 12 years old

i'd say that mort was 6 but now he's 8

Hmm I'd say that Private is about 14/15, Kowalski and Rico in their early 20's, and Skipper in his mid 20's.

I would say around 13-14, maaaybe 15.

Skipper 37-38
Kowalski 25-26
Rico 20-21
Private 15-16

I'd say he's 16 or 17. He can't be in the puberty penguin years because he doesn't have down feathers.

15-21 to be exact (in my opinion I mean)

Edit (10.28.13): I actually think more like 18-22, now.

...
Analysis time! :D
Here is how I break down adding human ages to Penguin growth and maturing. This is just a theory and is not a hard and fast rule for every penguin character in existence, it's just a basic chart that is for adding anthropomorphism to the PoM penguin growth process.
1. 0-10 yrs: Baby/child penguin:covered in down feathers, prepubescent.
2. 12-17:"Teen" penguin:down feathers start to be replaced, maturing starts (growth, more adult body, ect.)
3. 18-25: Young Adult Penguin- All feathers are replaced, but not totally matured in all areas. (may be full grown, but not socially, psychologically, or emotionally, those areas of the personality are still being developed. Or vica-versa, meaning the body may be feathered but also immature physically, yet in other areas matured.)
4. 25-onward: Fully Matured- No more growth in body, personality and psyche has been more firmly placed. ( I place Skipper, Kowalksi, and Rico here. Although I don't think anything logical can apply to Rico. He can survive having a rocket launcher ( from the Big Stank) in his stomach that is ten times his size. He is the Pinkie Pie of PoM in that regard.)
So, with these characteristics in mind, I propose that Private is in the Young Adult stage for these reasons.
1. He has all of his adult feathers, but is shorter than all the others. This may be his permanent height or perhaps he has not fully matured in this area.
2. His behavior and psyche waver between adult and child/preteen-ish. He loves the Lunacorns( and all things innocent, but that part is fine to stick for me. XD), but also is a fighter and knows how to to take charge of a situation.
I would like to say that despite Privates panicked behavior in high moltage, it was not the first time he had molted based on my chart. My explanation? Most molting cycles occur slowly, each feather comes off as the new one comes in. However, Privates hyper-cute had, as Kowalski said " Started it off with a bang" and knocked the old feathers out before the new ones had time to come in. So, instead of it being Private's first molting cycle, I reason that is was his first molting cycle after discovering and trying to use the Hyper-cute.
Specifically, I think of him as nineteen years old.
Also, another explanation. Private is British. British penguins are to awesome to comply with our logic in regard to age and behavior collaborating, so Private could be 50 or 6 or 56 and he'd still be the way he is (adorable).

I think 22-24

how do I add another answer

let me add another answer

@trisha1: You can't add another answer unless the maker of the poll checks the box when he/she makes the question. In this case, all you can do is comment your answer, like dejavu2571 did.

I'd say 15 or 14. :)

hes definitly little. a more spisific age I think hes 10

I agree completely with JediPenguin16. He may still like the Lunacorns, but he is very mature. His vocabulary may not be anywhere near as strong as Kowalski's, but Private definitely does use a mature vocab a lot of the time. And, if Private was a young teen, I think the other penguins would be much more protective of him. Private is able to 'leave their sights' and go off on typically dangerous missions on his own; they identify Private's maturity. Because Private does handle situations very well. Plus I don't think Skipper would let a child join his team, he calls his team 'men', not just 'men and Private'. And that whole thing in 'Love Hurts' with Shawna. Shawna was an intern, and young interns are therefore about 18 years old, maybe a little younger, maybe a little older. And the producers purposely used a woman character around that age to make sure it fitted with Private's age too, so there'd be nothing iffy about it, except obviously for the fact that she's human and he's penguin. But hey-ho who're we to judge? :)

I think Private would be about 18, Rico between 23 and 28, Skipper between 30 and 34, and Kowalski I think would be about 35 or 36. :) Marlene would maybe be in her late 20's. And Doris maybe in her late 20's too, maybe early 30's.

So hard to judge... but... I don't think he's a child... I had a really good reason for thinking this, but... I can't remember it. XP

He´s a kid. A sweet innocent child. xP He´s around 12 in human yrs.

12 or younger

Around 18 - 20. Sometimes, he's a little childish; but the other penguins accept him as part of their own. Sure, they don't let him hear or see specific things, but he is a "college boy." We also know he's old enough to have a interesting past (Mr. Tux, Badgers, and Butterscotch lolly trees).

I think between 9 to some where in the teens like 14